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json/api/basic_json/operator%3D.md
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2026-07-08 18:19:46 +00:00

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# <small>nlohmann::basic_json::</small>operator=
```cpp
basic_json& operator=(basic_json other) noexcept (
std::is_nothrow_move_constructible<value_t>::value &&
std::is_nothrow_move_assignable<value_t>::value &&
std::is_nothrow_move_constructible<json_value>::value &&
std::is_nothrow_move_assignable<json_value>::value &&
std::is_nothrow_move_assignable<json_base_class_t>::value
);
```
Copy assignment operator. Copies a JSON value via the "copy and swap" strategy: It is expressed in terms of the copy
constructor, destructor, and the `swap()` member function.
## Parameters
`other` (in)
: value to copy from
## Exception safety
Strong guarantee: if an exception is thrown while copying `other`, there are no changes to `#!cpp *this`.
## Complexity
Linear.
## Examples
??? example
The code below shows and example for the copy assignment. It creates a copy of value `a` which is then swapped with
`b`. Finally, the copy of `a` (which is the null value after the swap) is destroyed.
```cpp
--8<-- "examples/basic_json__copyassignment.cpp"
```
Output:
```json
--8<-- "examples/basic_json__copyassignment.output"
```
## See also
- [basic_json](basic_json.md) create a JSON value
- [swap](swap.md) exchanges the contents of two JSON values
## Version history
- Added in version 1.0.0.