json/doc/mkdocs/docs/api/basic_json/operator_gtgt.md

operator>>(basic_json)

std::istream& operator>>(std::istream& i, basic_json& j);

Deserializes an input stream to a JSON value.

Parameters

i (in, out)

input stream to read a serialized JSON value from

j (in, out)

JSON value to write the deserialized input to

Return value

the stream i

Exceptions

• Throws parse_error.101 in case of an unexpected token.
• Throws parse_error.102 if to_unicode fails or surrogate error.
• Throws parse_error.103 if to_unicode fails.

Complexity

Linear in the length of the input. The parser is a predictive LL(1) parser.

Notes

A UTF-8 byte order mark is silently ignored.

Examples

??? example

The example below shows how a JSON value is constructed by reading a serialization from a stream.
    
```cpp
--8<-- "examples/operator_deserialize.cpp"
```

Output:

```json
--8<-- "examples/operator_deserialize.output"
```

See also

• accept - check if the input is valid JSON
• parse - deserialize from a compatible input

Version history

• Added in version 1.0.0

!!! warning "Deprecation"

This function replaces function `#!cpp std::istream& operator<<(basic_json& j, std::istream& i)` which has
been deprecated in version 3.0.0. It will be removed in version 4.0.0. Please replace calls like `#!cpp j << i;`
with `#!cpp i >> j;`.