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<!doctype html> < html lang = en class = no-js > < head > < meta charset = utf-8 > < meta name = viewport content = "width=device-width,initial-scale=1" > < meta name = author content = "Niels Lohmann" > < link href = https://json.nlohmann.me/api/macros/nlohmann_json_serialize_enum/ rel = canonical > < link rel = icon href = ../../../assets/images/favicon.png > < meta name = generator content = "mkdocs-1.4.2, mkdocs-material-8.5.10" > < title > NLOHMANN_JSON_SERIALIZE_ENUM - JSON for Modern C++< / title > < link rel = stylesheet href = ../../../assets/stylesheets/main.975780f9.min.css > < link rel = stylesheet href = ../../../assets/stylesheets/palette.2505c338.min.css > < link rel = preconnect href = https://fonts.gstatic.com crossorigin > < link rel = stylesheet href = "https://fonts.googleapis.com/css?family=Roboto:300,300i,400,400i,700,700i%7CJetBrains+Mono:400,400i,700,700i&display=fallback" > < style > : root { --md-text-font : "Roboto" ; --md-code-font : "JetBrains Mono" } < / style > < link rel = stylesheet href = ../../../css/custom.css > < script > _ _md _scope = new URL ( "../../.." , location ) , _ _md _hash = e => [ ... e ] . reduce ( ( e , _ ) => ( e << 5 ) - e + _ . charCodeAt ( 0 ) , 0 ) , _ _md _get = ( e , _ = localStorage , t = _ _md _scope ) => JSON . parse ( _ . getItem ( t . pathname + "." + e ) ) , _ _md _set = ( e , _ , t = localStorage , a = _ _md _scope ) => { try { t . setItem ( a . pathname + "." + e , JSON . stringify ( _ ) ) } catch ( e ) { } } < / script > < / head > < body dir = ltr data-md-color-scheme = default data-md-color-primary = indigo data-md-color-accent = indigo > < script > var palette = _ _md _get ( "__palette" ) ; if ( palette && "object" == typeof palette . color ) for ( var key of Object . keys ( palette . color ) ) document . body . setAttribute ( "data-md-color-" + key , palette . color [ key ] ) < / script > < input class = md-toggle data-md-toggle = drawer type = checkbox id = __drawer autocomplete = off > < input class = md-toggle data-md-toggle = search type = checkbox id = __search autocomplete = off > < label class = md-overlay for = __drawer > < / label > < div data-md-component = skip > < a href = #nlohmann_json_serialize_enum class = md-skip > Skip to content < / a > < / div > < div data-md-component = announce > < / div > < header class = md-header data-md-component = header > < nav class = "md-header__inner md-grid" aria-label = Header > < a href = ../../.. title = "JSON for Modern C++" class = "md-header__button md-logo" aria-label = "JSON for Modern C++" data-md-component = logo > < svg xmlns = http://www.w3.org/2000/svg viewbox = "0 0 24 24" > < path d = "M12 8a3 3 0 0 0 3-3 3 3 0 0 0-3-3 3 3 0 0 0-3 3 3 3 0 0 0 3 3m0 3.54C9.64 9.35 6.5 8 3 8v11c3.5 0 6.64 1.35 9 3.54 2.36-2.19 5.5-3.54 9-3.54V8c-3.5 0-6.64 1.35-9 3.54Z" / > < / svg > < / a > < label class = "md-header__button md-icon" for = __drawer > < svg xmlns = http://www.w3.org/2000/svg viewbox = "0 0 24 24" > < path d = "M3 6h18v2H3V6m0 5h18v2H3v-2m0 5h18v2H3v-2Z" / > < / svg > < / label > < div class = md-header__title data-md-component = header-title > < div class = md-header__ellipsis > < div class = md-header__topic > < span class = md-ellipsis > JSON for Modern C++ < / span > < / div > < div class = md-header__topic data-md-component = header-topic > < span class = md-ellipsis > NLOHMANN_JSON_SERIALIZE_ENUM < / span > < / div > < / div > < / div > < form class = md-header__option data-md-component = palette > < input class = md-option data-md-color-media = "(prefers-color-scheme: light)" data-md-color-scheme = default data-md-color-primary = indigo data-md-color-accent = indigo aria-label = "Switch to dark mode" type = radio name = __palette id = __palette_1 > < label class = "md-header__button md-icon" title = "Switch to dark mode" for = __palette_2 hidden > < svg xmlns = http://www.w3.org/2000/svg viewbox = "0 0 24 24" > < path d = "M12 8a4 4 0 0 0-4 4 4 4 0 0 0 4 4 4 4 0 0 0 4-4 4 4 0 0 0-4-4m0 10a6 6 0 0 1-6-6 6 6 0 0 1 6-6 6 6 0 0 1 6 6 6 6 0 0 1-6 6m8-9.31V4h-4.69L12 .69 8.69 4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12 20 8.69Z" / > < / svg > < / label > < input class = md-option data-md-color-media = "(prefers-color-scheme: dark)" data-md-color-scheme = slate data-md-color-primary = indigo data-md-color-accent = indigo aria-label = "Switch to light mode" type = radio name = __palette id = __palette_2 > < label class = "md-header__button md-icon" title = "Switch to light mode" for = __palette_1 hidden > < svg xmlns = http://www.w3.org/2000/svg viewbox = "0 0 24 24" > < path d = "M12 18c- . 89 0-1 . 74- . 2-2 . 5- . 55C11 . 56 16 . 5 13 14 . 42 13 12
< / code > < / pre > < / div > < p > By default, enum values are serialized to JSON as integers. In some cases this could result in undesired behavior. If an enum is modified or re-ordered after data has been serialized to JSON, the later de-serialized JSON data may be undefined or a different enum value than was originally intended.< / p > < p > The < code > NLOHMANN_JSON_SERIALIZE_ENUM< / code > allows to define a user-defined serialization for every enumerator.< / p > < h2 id = parameters > Parameters< a class = headerlink href = #parameters title = "Permanent link" > ¶ < / a > < / h2 > < dl > < dt > < code > type< / code > (in)< / dt > < dd > name of the enum to serialize/deserialize< / dd > < dt > < code > conversion< / code > (in)< / dt > < dd > a pair of an enumerator and a JSON serialization; arbitrary pairs can be given as a comma-separated list< / dd > < / dl > < h2 id = default-definition > Default definition< a class = headerlink href = #default-definition title = "Permanent link" > ¶ < / a > < / h2 > < p > The macros add two friend functions to the class which take care of the serialization and deserialization:< / p > < div class = highlight > < pre > < span > < / span > < code > < span class = k > template< / span > < span class = o > < < / span > < span class = k > typename< / span > < span class = w > < / span > < span class = nc > BasicJsonType< / span > < span class = o > > < / span > < span class = w > < / span >
< span class = kr > inline< / span > < span class = w > < / span > < span class = kt > void< / span > < span class = w > < / span > < span class = n > to_json< / span > < span class = p > (< / span > < span class = n > BasicJsonType< / span > < span class = o > & < / span > < span class = w > < / span > < span class = n > j< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = k > const< / span > < span class = w > < / span > < span class = n > type< / span > < span class = o > & < / span > < span class = w > < / span > < span class = n > e< / span > < span class = p > );< / span > < span class = w > < / span >
< span class = k > template< / span > < span class = o > < < / span > < span class = k > typename< / span > < span class = w > < / span > < span class = nc > BasicJsonType< / span > < span class = o > > < / span > < span class = w > < / span >
< span class = kr > inline< / span > < span class = w > < / span > < span class = kt > void< / span > < span class = w > < / span > < span class = n > from_json< / span > < span class = p > (< / span > < span class = k > const< / span > < span class = w > < / span > < span class = n > BasicJsonType< / span > < span class = o > & < / span > < span class = w > < / span > < span class = n > j< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = n > type< / span > < span class = o > & < / span > < span class = w > < / span > < span class = n > e< / span > < span class = p > );< / span > < span class = w > < / span >
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< / code > < / pre > < / div > < h2 id = notes > Notes< a class = headerlink href = #notes title = "Permanent link" > ¶ < / a > < / h2 > < div class = "admonition info" > < p class = admonition-title > Prerequisites< / p > < p > The macro must be used inside the namespace of the enum.< / p > < / div > < div class = "admonition important" > < p class = admonition-title > Important notes< / p > < ul > < li > When using < a href = ../../basic_json/get/ > < code > template get< ENUM_TYPE> ()< / code > < / a > , undefined JSON values will default to the first specified conversion. Select this default pair carefully. See example 1 below.< / li > < li > If an enum or JSON value is specified in multiple conversions, the first matching conversion from the top of the list will be returned when converting to or from JSON. See example 2 below.< / li > < / ul > < / div > < h2 id = examples > Examples< a class = headerlink href = #examples title = "Permanent link" > ¶ < / a > < / h2 > < details class = example > < summary > Example 1: Basic usage< / summary > < p > The example shows how < code > NLOHMANN_JSON_SERIALIZE_ENUM< / code > can be used to serialize/deserialize both classical enums and C++11 enum classes:< / p > < div class = highlight > < pre > < span > < / span > < code > < span class = cp > #include< / span > < span class = w > < / span > < span class = cpf > < iostream> < / span > < span class = cp > < / span >
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< span class = cp > #include< / span > < span class = w > < / span > < span class = cpf > < nlohmann/json.hpp> < / span > < span class = cp > < / span >
< span class = k > using< / span > < span class = w > < / span > < span class = n > json< / span > < span class = w > < / span > < span class = o > =< / span > < span class = w > < / span > < span class = n > nlohmann< / span > < span class = o > ::< / span > < span class = n > json< / span > < span class = p > ;< / span > < span class = w > < / span >
< span class = k > namespace< / span > < span class = w > < / span > < span class = nn > ns< / span > < span class = w > < / span >
< span class = p > {< / span > < span class = w > < / span >
< span class = k > enum< / span > < span class = w > < / span > < span class = nc > TaskState< / span > < span class = w > < / span >
< span class = p > {< / span > < span class = w > < / span >
< span class = w > < / span > < span class = n > TS_STOPPED< / span > < span class = p > ,< / span > < span class = w > < / span >
< span class = w > < / span > < span class = n > TS_RUNNING< / span > < span class = p > ,< / span > < span class = w > < / span >
< span class = w > < / span > < span class = n > TS_COMPLETED< / span > < span class = p > ,< / span > < span class = w > < / span >
< span class = w > < / span > < span class = n > TS_INVALID< / span > < span class = w > < / span > < span class = o > =< / span > < span class = w > < / span > < span class = mi > -1< / span > < span class = w > < / span >
< span class = p > };< / span > < span class = w > < / span >
< span class = hll > < span class = n > NLOHMANN_JSON_SERIALIZE_ENUM< / span > < span class = p > (< / span > < span class = n > TaskState< / span > < span class = p > ,< / span > < span class = w > < / span >
< / span > < span class = hll > < span class = p > {< / span > < span class = w > < / span >
< / span > < span class = hll > < span class = w > < / span > < span class = p > {< / span > < span class = w > < / span > < span class = n > TS_INVALID< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = k > nullptr< / span > < span class = w > < / span > < span class = p > },< / span > < span class = w > < / span >
< / span > < span class = hll > < span class = w > < / span > < span class = p > {< / span > < span class = w > < / span > < span class = n > TS_STOPPED< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = s > " stopped" < / span > < span class = w > < / span > < span class = p > },< / span > < span class = w > < / span >
< / span > < span class = hll > < span class = w > < / span > < span class = p > {< / span > < span class = w > < / span > < span class = n > TS_RUNNING< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = s > " running" < / span > < span class = w > < / span > < span class = p > },< / span > < span class = w > < / span >
< / span > < span class = hll > < span class = w > < / span > < span class = p > {< / span > < span class = w > < / span > < span class = n > TS_COMPLETED< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = s > " completed" < / span > < span class = w > < / span > < span class = p > }< / span > < span class = w > < / span >
< / span > < span class = hll > < span class = p > })< / span > < span class = w > < / span >
< / span >
< span class = k > enum< / span > < span class = w > < / span > < span class = k > class< / span > < span class = w > < / span > < span class = nc > Color< / span > < span class = w > < / span >
< span class = p > {< / span > < span class = w > < / span >
< span class = w > < / span > < span class = n > red< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = n > green< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = n > blue< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = n > unknown< / span > < span class = w > < / span >
< span class = p > };< / span > < span class = w > < / span >
< span class = hll > < span class = n > NLOHMANN_JSON_SERIALIZE_ENUM< / span > < span class = p > (< / span > < span class = n > Color< / span > < span class = p > ,< / span > < span class = w > < / span >
< / span > < span class = hll > < span class = p > {< / span > < span class = w > < / span >
< / span > < span class = hll > < span class = w > < / span > < span class = p > {< / span > < span class = w > < / span > < span class = n > Color< / span > < span class = o > ::< / span > < span class = n > unknown< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = s > " unknown" < / span > < span class = w > < / span > < span class = p > },< / span > < span class = w > < / span > < span class = p > {< / span > < span class = w > < / span > < span class = n > Color< / span > < span class = o > ::< / span > < span class = n > red< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = s > " red" < / span > < span class = w > < / span > < span class = p > },< / span > < span class = w > < / span >
< / span > < span class = hll > < span class = w > < / span > < span class = p > {< / span > < span class = w > < / span > < span class = n > Color< / span > < span class = o > ::< / span > < span class = n > green< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = s > " green" < / span > < span class = w > < / span > < span class = p > },< / span > < span class = w > < / span > < span class = p > {< / span > < span class = w > < / span > < span class = n > Color< / span > < span class = o > ::< / span > < span class = n > blue< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = s > " blue" < / span > < span class = w > < / span > < span class = p > }< / span > < span class = w > < / span >
< / span > < span class = hll > < span class = p > })< / span > < span class = w > < / span >
< / span > < span class = p > }< / span > < span class = w > < / span > < span class = c1 > // namespace ns< / span >
< span class = kt > int< / span > < span class = w > < / span > < span class = n > main< / span > < span class = p > ()< / span > < span class = w > < / span >
< span class = p > {< / span > < span class = w > < / span >
< span class = w > < / span > < span class = c1 > // serialization< / span >
< span class = w > < / span > < span class = n > json< / span > < span class = w > < / span > < span class = n > j_stopped< / span > < span class = w > < / span > < span class = o > =< / span > < span class = w > < / span > < span class = n > ns< / span > < span class = o > ::< / span > < span class = n > TS_STOPPED< / span > < span class = p > ;< / span > < span class = w > < / span >
< span class = w > < / span > < span class = n > json< / span > < span class = w > < / span > < span class = n > j_red< / span > < span class = w > < / span > < span class = o > =< / span > < span class = w > < / span > < span class = n > ns< / span > < span class = o > ::< / span > < span class = n > Color< / span > < span class = o > ::< / span > < span class = n > red< / span > < span class = p > ;< / span > < span class = w > < / span >
< span class = w > < / span > < span class = n > std< / span > < span class = o > ::< / span > < span class = n > cout< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = s > " ns::TS_STOPPED -> " < / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = n > j_stopped< / span > < span class = w > < / span >
< span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = s > " , ns::Color::red -> " < / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = n > j_red< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = n > std< / span > < span class = o > ::< / span > < span class = n > endl< / span > < span class = p > ;< / span > < span class = w > < / span >
< span class = w > < / span > < span class = c1 > // deserialization< / span >
< span class = w > < / span > < span class = n > json< / span > < span class = w > < / span > < span class = n > j_running< / span > < span class = w > < / span > < span class = o > =< / span > < span class = w > < / span > < span class = s > " running" < / span > < span class = p > ;< / span > < span class = w > < / span >
< span class = w > < / span > < span class = n > json< / span > < span class = w > < / span > < span class = n > j_blue< / span > < span class = w > < / span > < span class = o > =< / span > < span class = w > < / span > < span class = s > " blue" < / span > < span class = p > ;< / span > < span class = w > < / span >
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< span class = w > < / span > < span class = k > auto< / span > < span class = w > < / span > < span class = n > running< / span > < span class = w > < / span > < span class = o > =< / span > < span class = w > < / span > < span class = n > j_running< / span > < span class = p > .< / span > < span class = k > template< / span > < span class = w > < / span > < span class = n > get< / span > < span class = o > < < / span > < span class = n > ns< / span > < span class = o > ::< / span > < span class = n > TaskState< / span > < span class = o > > < / span > < span class = p > ();< / span > < span class = w > < / span >
< span class = w > < / span > < span class = k > auto< / span > < span class = w > < / span > < span class = n > blue< / span > < span class = w > < / span > < span class = o > =< / span > < span class = w > < / span > < span class = n > j_blue< / span > < span class = p > .< / span > < span class = k > template< / span > < span class = w > < / span > < span class = n > get< / span > < span class = o > < < / span > < span class = n > ns< / span > < span class = o > ::< / span > < span class = n > Color< / span > < span class = o > > < / span > < span class = p > ();< / span > < span class = w > < / span >
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< span class = w > < / span > < span class = n > std< / span > < span class = o > ::< / span > < span class = n > cout< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = n > j_running< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = s > " -> " < / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = n > running< / span > < span class = w > < / span >
< span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = s > " , " < / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = n > j_blue< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = s > " -> " < / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = k > static_cast< / span > < span class = o > < < / span > < span class = kt > int< / span > < span class = o > > < / span > < span class = p > (< / span > < span class = n > blue< / span > < span class = p > )< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = n > std< / span > < span class = o > ::< / span > < span class = n > endl< / span > < span class = p > ;< / span > < span class = w > < / span >
< span class = w > < / span > < span class = c1 > // deserializing undefined JSON value to enum< / span >
< span class = w > < / span > < span class = c1 > // (where the first map entry above is the default)< / span >
< span class = w > < / span > < span class = n > json< / span > < span class = w > < / span > < span class = n > j_pi< / span > < span class = w > < / span > < span class = o > =< / span > < span class = w > < / span > < span class = mf > 3.14< / span > < span class = p > ;< / span > < span class = w > < / span >
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< span class = w > < / span > < span class = k > auto< / span > < span class = w > < / span > < span class = n > invalid< / span > < span class = w > < / span > < span class = o > =< / span > < span class = w > < / span > < span class = n > j_pi< / span > < span class = p > .< / span > < span class = k > template< / span > < span class = w > < / span > < span class = n > get< / span > < span class = o > < < / span > < span class = n > ns< / span > < span class = o > ::< / span > < span class = n > TaskState< / span > < span class = o > > < / span > < span class = p > ();< / span > < span class = w > < / span >
< span class = w > < / span > < span class = k > auto< / span > < span class = w > < / span > < span class = n > unknown< / span > < span class = w > < / span > < span class = o > =< / span > < span class = w > < / span > < span class = n > j_pi< / span > < span class = p > .< / span > < span class = k > template< / span > < span class = w > < / span > < span class = n > get< / span > < span class = o > < < / span > < span class = n > ns< / span > < span class = o > ::< / span > < span class = n > Color< / span > < span class = o > > < / span > < span class = p > ();< / span > < span class = w > < / span >
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< span class = w > < / span > < span class = n > std< / span > < span class = o > ::< / span > < span class = n > cout< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = n > j_pi< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = s > " -> " < / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = n > invalid< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = s > " , " < / span > < span class = w > < / span >
< span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = n > j_pi< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = s > " -> " < / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = k > static_cast< / span > < span class = o > < < / span > < span class = kt > int< / span > < span class = o > > < / span > < span class = p > (< / span > < span class = n > unknown< / span > < span class = p > )< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = n > std< / span > < span class = o > ::< / span > < span class = n > endl< / span > < span class = p > ;< / span > < span class = w > < / span >
< span class = p > }< / span > < span class = w > < / span >
< / code > < / pre > < / div > < p > Output:< / p > < div class = highlight > < pre > < span > < / span > < code > < span class = kc > ns< / span > < span class = p > ::< / span > < span class = err > TS_STOPPED< / span > < span class = w > < / span > < span class = mi > -< / span > < span class = err > > < / span > < span class = w > < / span > < span class = s2 > " stopped" < / span > < span class = p > ,< / span > < span class = w > < / span > < span class = kc > ns< / span > < span class = p > ::< / span > < span class = err > Color< / span > < span class = p > ::< / span > < span class = err > red< / span > < span class = w > < / span > < span class = mi > -< / span > < span class = err > > < / span > < span class = w > < / span > < span class = s2 > " red" < / span > < span class = w > < / span >
< span class = s2 > " running" < / span > < span class = w > < / span > < span class = mi > -< / span > < span class = err > > < / span > < span class = w > < / span > < span class = mi > 1< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = s2 > " blue" < / span > < span class = w > < / span > < span class = mi > -< / span > < span class = err > > < / span > < span class = w > < / span > < span class = mi > 2< / span > < span class = w > < / span >
< span class = mf > 3.14< / span > < span class = w > < / span > < span class = mi > -< / span > < span class = err > > < / span > < span class = w > < / span > < span class = mi > -1< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = mf > 3.14< / span > < span class = w > < / span > < span class = mi > -< / span > < span class = err > > < / span > < span class = w > < / span > < span class = mi > 3< / span > < span class = w > < / span >
< / code > < / pre > < / div > < / details > < details class = example > < summary > Example 2: Multiple conversions for one enumerator< / summary > < p > The example shows how to use multiple conversions for a single enumerator. In the example, < code > Color::red< / code > will always be < em > serialized< / em > to < code > "red"< / code > , because the first occurring conversion. The second conversion, however, offers an alternative < em > deserialization< / em > from < code > "rot"< / code > to < code > Color::red< / code > .< / p > < div class = highlight > < pre > < span > < / span > < code > < span class = cp > #include< / span > < span class = w > < / span > < span class = cpf > < iostream> < / span > < span class = cp > < / span >
< span class = cp > #include< / span > < span class = w > < / span > < span class = cpf > < nlohmann/json.hpp> < / span > < span class = cp > < / span >
< span class = k > using< / span > < span class = w > < / span > < span class = n > json< / span > < span class = w > < / span > < span class = o > =< / span > < span class = w > < / span > < span class = n > nlohmann< / span > < span class = o > ::< / span > < span class = n > json< / span > < span class = p > ;< / span > < span class = w > < / span >
< span class = k > namespace< / span > < span class = w > < / span > < span class = nn > ns< / span > < span class = w > < / span >
< span class = p > {< / span > < span class = w > < / span >
< span class = k > enum< / span > < span class = w > < / span > < span class = k > class< / span > < span class = w > < / span > < span class = nc > Color< / span > < span class = w > < / span >
< span class = p > {< / span > < span class = w > < / span >
< span class = w > < / span > < span class = n > red< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = n > green< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = n > blue< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = n > unknown< / span > < span class = w > < / span >
< span class = p > };< / span > < span class = w > < / span >
< span class = n > NLOHMANN_JSON_SERIALIZE_ENUM< / span > < span class = p > (< / span > < span class = n > Color< / span > < span class = p > ,< / span > < span class = w > < / span >
< span class = p > {< / span > < span class = w > < / span >
< span class = w > < / span > < span class = p > {< / span > < span class = w > < / span > < span class = n > Color< / span > < span class = o > ::< / span > < span class = n > unknown< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = s > " unknown" < / span > < span class = w > < / span > < span class = p > },< / span > < span class = w > < / span > < span class = p > {< / span > < span class = w > < / span > < span class = n > Color< / span > < span class = o > ::< / span > < span class = n > red< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = s > " red" < / span > < span class = w > < / span > < span class = p > },< / span > < span class = w > < / span >
< span class = w > < / span > < span class = p > {< / span > < span class = w > < / span > < span class = n > Color< / span > < span class = o > ::< / span > < span class = n > green< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = s > " green" < / span > < span class = w > < / span > < span class = p > },< / span > < span class = w > < / span > < span class = p > {< / span > < span class = w > < / span > < span class = n > Color< / span > < span class = o > ::< / span > < span class = n > blue< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = s > " blue" < / span > < span class = w > < / span > < span class = p > },< / span > < span class = w > < / span >
< span class = hll > < span class = w > < / span > < span class = p > {< / span > < span class = w > < / span > < span class = n > Color< / span > < span class = o > ::< / span > < span class = n > red< / span > < span class = p > ,< / span > < span class = w > < / span > < span class = s > " rot" < / span > < span class = w > < / span > < span class = p > }< / span > < span class = w > < / span > < span class = c1 > // a second conversion for Color::red< / span >
< / span > < span class = p > })< / span > < span class = w > < / span >
< span class = p > }< / span > < span class = w > < / span >
< span class = kt > int< / span > < span class = w > < / span > < span class = n > main< / span > < span class = p > ()< / span > < span class = w > < / span >
< span class = p > {< / span > < span class = w > < / span >
< span class = w > < / span > < span class = c1 > // serialization< / span >
< span class = w > < / span > < span class = n > json< / span > < span class = w > < / span > < span class = n > j_red< / span > < span class = w > < / span > < span class = o > =< / span > < span class = w > < / span > < span class = n > ns< / span > < span class = o > ::< / span > < span class = n > Color< / span > < span class = o > ::< / span > < span class = n > red< / span > < span class = p > ;< / span > < span class = w > < / span >
< span class = w > < / span > < span class = n > std< / span > < span class = o > ::< / span > < span class = n > cout< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = k > static_cast< / span > < span class = o > < < / span > < span class = kt > int< / span > < span class = o > > < / span > < span class = p > (< / span > < span class = n > ns< / span > < span class = o > ::< / span > < span class = n > Color< / span > < span class = o > ::< / span > < span class = n > red< / span > < span class = p > )< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = s > " -> " < / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = n > j_red< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = n > std< / span > < span class = o > ::< / span > < span class = n > endl< / span > < span class = p > ;< / span > < span class = w > < / span >
< span class = w > < / span > < span class = c1 > // deserialization< / span >
< span class = w > < / span > < span class = n > json< / span > < span class = w > < / span > < span class = n > j_rot< / span > < span class = w > < / span > < span class = o > =< / span > < span class = w > < / span > < span class = s > " rot" < / span > < span class = p > ;< / span > < span class = w > < / span >
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< span class = w > < / span > < span class = k > auto< / span > < span class = w > < / span > < span class = n > rot< / span > < span class = w > < / span > < span class = o > =< / span > < span class = w > < / span > < span class = n > j_rot< / span > < span class = p > .< / span > < span class = k > template< / span > < span class = w > < / span > < span class = n > get< / span > < span class = o > < < / span > < span class = n > ns< / span > < span class = o > ::< / span > < span class = n > Color< / span > < span class = o > > < / span > < span class = p > ();< / span > < span class = w > < / span >
< span class = w > < / span > < span class = k > auto< / span > < span class = w > < / span > < span class = n > red< / span > < span class = w > < / span > < span class = o > =< / span > < span class = w > < / span > < span class = n > j_red< / span > < span class = p > .< / span > < span class = k > template< / span > < span class = w > < / span > < span class = n > get< / span > < span class = o > < < / span > < span class = n > ns< / span > < span class = o > ::< / span > < span class = n > Color< / span > < span class = o > > < / span > < span class = p > ();< / span > < span class = w > < / span >
2023-03-08 15:43:29 +03:00
< span class = w > < / span > < span class = n > std< / span > < span class = o > ::< / span > < span class = n > cout< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = n > j_rot< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = s > " -> " < / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = k > static_cast< / span > < span class = o > < < / span > < span class = kt > int< / span > < span class = o > > < / span > < span class = p > (< / span > < span class = n > rot< / span > < span class = p > )< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = n > std< / span > < span class = o > ::< / span > < span class = n > endl< / span > < span class = p > ;< / span > < span class = w > < / span >
< span class = w > < / span > < span class = n > std< / span > < span class = o > ::< / span > < span class = n > cout< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = n > j_red< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = s > " -> " < / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = k > static_cast< / span > < span class = o > < < / span > < span class = kt > int< / span > < span class = o > > < / span > < span class = p > (< / span > < span class = n > red< / span > < span class = p > )< / span > < span class = w > < / span > < span class = o > < < < / span > < span class = w > < / span > < span class = n > std< / span > < span class = o > ::< / span > < span class = n > endl< / span > < span class = p > ;< / span > < span class = w > < / span >
< span class = p > }< / span > < span class = w > < / span >
< / code > < / pre > < / div > < p > Output:< / p > < div class = highlight > < pre > < span > < / span > < code > < span class = mi > 0< / span > < span class = w > < / span > < span class = mi > -< / span > < span class = err > > < / span > < span class = w > < / span > < span class = s2 > " red" < / span > < span class = w > < / span >
< span class = s2 > " rot" < / span > < span class = w > < / span > < span class = mi > -< / span > < span class = err > > < / span > < span class = w > < / span > < span class = mi > 0< / span > < span class = w > < / span >
< span class = s2 > " red" < / span > < span class = w > < / span > < span class = mi > -< / span > < span class = err > > < / span > < span class = w > < / span > < span class = mi > 0< / span > < span class = w > < / span >
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< / code > < / pre > < / div > < / details > < h2 id = see-also > See also< a class = headerlink href = #see-also title = "Permanent link" > ¶ < / a > < / h2 > < ul > < li > < a href = ../../../features/enum_conversion/ > Specializing enum conversion< / a > < / li > < li > < a href = ../json_disable_enum_serialization/ > < code > JSON_DISABLE_ENUM_SERIALIZATION< / code > < / a > < / li > < / ul > < h2 id = version-history > Version history< a class = headerlink href = #version-history title = "Permanent link" > ¶ < / a > < / h2 > < p > Added in version 3.4.0.< / p > < hr > < div class = md-source-file > < small > Last update: < span class = "git-revision-date-localized-plugin git-revision-date-localized-plugin-date" > June 11, 2023< / span > < / small > < / div > < / article > < / div > < script > var tabs = _ _md _get ( "__tabs" ) ; if ( Array . isArray ( tabs ) ) e : for ( var set of document . querySelectorAll ( ".tabbed-set" ) ) { var tab , labels = set . querySelector ( ".tabbed-labels" ) ; for ( tab of tabs ) for ( var label of labels . getElementsByTagName ( "label" ) ) if ( label . innerText . trim ( ) === tab ) { var input = document . getElementById ( label . htmlFor ) ; input . checked = ! 0 ; continue e } } < / script > < / div > < a href = # class = "md-top md-icon" data-md-component = top hidden > < svg xmlns = http://www.w3.org/2000/svg viewbox = "0 0 24 24" > < path d = "M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8v12Z" / > < / svg > Back to top < / a > < / main > < footer class = md-footer > < nav class = "md-footer__inner md-grid" aria-label = Footer > < a href = ../nlohmann_json_namespace_no_version/ class = "md-footer__link md-footer__link--prev" aria-label = "Previous: NLOHMANN_JSON_NAMESPACE_NO_VERSION" rel = prev > < div class = "md-footer__button md-icon" > < svg xmlns = http://www.w3.org/2000/svg viewbox = "0 0 24 24" > < path d = "M20 11v2H8l5.5 5.5-1.42 1.42L4.16 12l7.92-7.92L13.5 5.5 8 11h12Z" / > < / svg > < / div > < div class = md-footer__title > < div class = md-ellipsis > < span class = md-footer__direction > Previous < / span > NLOHMANN_JSON_NAMESPACE_NO_VERSION < / div > < / div > < / a > < a href = ../nlohmann_json_version_major/ class = "md-footer__link md-footer__link--next" aria-label = "Next: NLOHMANN_JSON_VERSION_MAJOR" rel = next > < div class = md-footer__title > < div class = md-ellipsis > < span class = md-footer__direction > Next < / span > NLOHMANN_JSON_VERSION_MAJOR < / div > < / div > < div class = "md-footer__button md-icon" > < svg xmlns = http://www.w3.org/2000/svg viewbox = "0 0 24 24" > < path d = "M4 11v2h12l-5.5 5.5 1.42 1.42L19.84 12l-7.92-7.92L10.5 5.5 16 11H4Z" / > < / svg > < / div > < / a > < / nav > < div class = "md-footer-meta md-typeset" > < div class = "md-footer-meta__inner md-grid" > < div class = md-copyright > < div class = md-copyright__highlight > Copyright © 2013 - 2022 Niels Lohmann < / div > < / div > < div class = md-social > < a href = https://github.com/nlohmann target = _blank rel = noopener title = github.com class = md-social__link > < svg xmlns = http://www.w3.org/2000/svg viewbox = "0 0 496 512" > <!-- Font Awesome Free 6.2.1 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2022 Fonticons, Inc. --> < path d = "M165.9 397 . 4c0 2-2 . 3 3 . 6-5 . 2 3 . 6-3 . 3 . 3-5 . 6-1 . 3-5 . 6-3 . 6 0-2 2 . 3-3 . 6 5 . 2-3 . 6 3- . 3 5 . 6 1 . 3 5 . 6 3 . 6zm-31 . 1-4 . 5c- . 7 2 1 . 3 4 . 3 4 . 3 4 . 9 2 . 6 1 5 . 6 0 6 . 2-2s-1 . 3-4 . 3-4 . 3-5 . 2c-2 . 6- . 7-5 . 5 . 3-6 . 2 2 . 3zm44 . 2-1 . 7c-2 . 9 . 7-4 . 9 2 . 6-4 . 6 4 . 9 . 3 2 2 . 9 3 . 3 5 . 9 2 . 6 2 . 9- . 7 4 . 9-2 . 6 4 . 6-4 . 6- . 3-1 . 9-3-3 . 2-5 . 9-2 . 9zM244 . 8 8C106 . 1 8 0 113 . 3 0 252c0 110 . 9 69 . 8 205 . 8 169 . 5 239 . 2 12 . 8 2 . 3 17 . 3-5 . 6 17 . 3-12 . 1 0-6 . 2- . 3-40 . 4- . 3-61 . 4 0 0-70 15-84 . 7-29 . 8 0 0-11 . 4-29 . 1-27 . 8-36 . 6 0 0-22 . 9-15 . 7 1 . 6-15 . 4 0 0 24 . 9 2 38 . 6 25 . 8 21 . 9 38 . 6 58 . 6 27 . 5 72 . 9 20 . 9 2 . 3-16 8 . 8-27 . 1 16-33 . 7-55 . 9-6 . 2-112 . 3-14 . 3-112 . 3-110 . 5 0-27 . 5 7 . 6-41 . 3 23 . 6-58 . 9-2 . 6-6 . 5-11 . 1-33 . 3 2 . 6-67 . 9 20 . 9-6 . 5 69 27 69 27 20-5 . 6 41 . 5-8 . 5 62 . 8-8 . 5s42 . 8 2 . 9 62 . 8 8 . 5c0 0 48 . 1-33 . 6 69-27 13 . 7 34 . 7 5 . 2 61 . 4 2 . 6 67 . 9 16 17 . 7 25 . 8 31 . 5 25 . 8 58 . 9 0 96 . 5-58 . 9 104 . 2-114 . 8 110 . 5 9 . 2 7 . 9 17 22 . 9 17 46 . 4 0 33 . 7- . 3 75 . 4- . 3 83 . 6 0 6 . 5 4 . 6 14 . 4 17 . 3 12 . 1C428 . 2 457 . 8 496 362 . 9 496 252 496 113 . 3 383 . 5 8 244 . 8 8zM97 . 2 352 . 9c-1 . 3 1-1 3 . 3 . 7 5 . 2 1 . 6 1 . 6 3 . 9 2 . 3 5 . 2 1 1 . 3-1 1-3 . 3- . 7-5 . 2-1 . 6-1 . 6-3 . 9-2 . 3-5 . 2-1zm-10 . 8-8 . 1c- . 7 1 . 3 . 3 2 . 9 2 . 3 3 . 9 1 . 6 1 3 . 6 . 7 4 . 3- . 7 . 7-1 . 3- . 3-2 . 9-2 . 3-3 . 9-2- . 6-3 . 6- . 3-4 . 3 . 7zm32 . 4 35 . 6c-1 . 6 1 . 3-1 4 . 3 1 . 3 6 . 2
