json/api/basic_json/std_swap.md

std::swap<basic_json>

namespace std {
    void swap(nlohmann::basic_json& j1, nlohmann::basic_json& j2);
}

Exchanges the values of two JSON objects.

Parameters

j1 (in, out)

value to be replaced by j2

j2 (in, out)

value to be replaced by j1

Exception safety

No-throw guarantee: this function never throws exceptions.

Complexity

Constant.

Possible implementation

void swap(nlohmann::basic_json& j1, nlohmann::basic_json& j2)
{
    j1.swap(j2);
}

Examples

??? example

The following code shows how two values are swapped with `std::swap`.
 
```cpp
#include <iostream>
#include <iomanip>
#include <nlohmann/json.hpp>

using json = nlohmann::json;

int main()
{
    // create JSON values
    json j1 = {{"one", 1}, {"two", 2}};
    json j2 = {1, 2, 4, 8, 16};

    std::cout << "j1 = " << j1 << " | j2 = " << j2 << '\n';

    // swap values
    std::swap(j1, j2);

    std::cout << "j1 = " << j1 << " | j2 = " << j2 << std::endl;
}

```

Output:

```json
j1 = {"one":1,"two":2} | j2 = [1,2,4,8,16]
j1 = [1,2,4,8,16] | j2 = {"one":1,"two":2}

```

See also

• swap

Version history

• Added in version 1.0.0.
• Extended for arbitrary basic_json types in version 3.10.5.