66 lines
1.5 KiB
Markdown
66 lines
1.5 KiB
Markdown
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# operator>>(basic_json)
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```cpp
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std::istream& operator>>(std::istream& i, basic_json& j);
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```
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Deserializes an input stream to a JSON value.
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## Parameters
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`i` (in, out)
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: input stream to read a serialized JSON value from
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`j` (in, out)
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: JSON value to write the deserialized input to
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## Return value
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the stream `i`
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## Exceptions
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- Throws [`parse_error.101`](../../home/exceptions.md#jsonexceptionparse_error101) in case of an unexpected token.
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- Throws [`parse_error.102`](../../home/exceptions.md#jsonexceptionparse_error102) if to_unicode fails or surrogate
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error.
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- Throws [`parse_error.103`](../../home/exceptions.md#jsonexceptionparse_error103) if to_unicode fails.
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## Complexity
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Linear in the length of the input. The parser is a predictive LL(1) parser.
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## Notes
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A UTF-8 byte order mark is silently ignored.
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## Examples
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??? example
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The example below shows how a JSON value is constructed by reading a serialization from a stream.
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```cpp
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--8<-- "examples/operator_deserialize.cpp"
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```
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Output:
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```json
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--8<-- "examples/operator_deserialize.output"
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```
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## See also
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- [accept](accept.md) - check if the input is valid JSON
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- [parse](parse.md) - deserialize from a compatible input
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## Version history
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- Added in version 1.0.0
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!!! warning "Deprecation"
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This function replaces function `#!cpp std::istream& operator<<(basic_json& j, std::istream& i)` which has
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been deprecated in version 3.0.0. It will be removed in version 4.0.0. Please replace calls like `#!cpp j << i;`
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with `#!cpp i >> j;`.
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