# <small>nlohmann::basic_json::</small>max_size

```cpp
size_type max_size() const noexcept;
```

Returns the maximum number of elements a JSON value is able to hold due to system or library implementation limitations,
i.e. `std::distance(begin(), end())` for the JSON value.
    
## Return value

The return value depends on the different types and is defined as follows:

| Value type | return value                              |
|------------|-------------------------------------------|
| null       | `0` (same as [`size()`](size.md))         |
| boolean    | `1` (same as [`size()`](size.md))         |
| string     | `1` (same as [`size()`](size.md))         |
| number     | `1` (same as [`size()`](size.md))         |
| binary     | `1` (same as [`size()`](size.md))         |
| object     | result of function `object_t::max_size()` |
| array      | result of function `array_t::max_size()`  |

## Exception safety

No-throw guarantee: this function never throws exceptions.

## Complexity

Constant, as long as [`array_t`](array_t.md) and [`object_t`](object_t.md) satisfy the
[Container](https://en.cppreference.com/w/cpp/named_req/Container) concept; that is, their `max_size()` functions have
constant complexity.

## Notes

This function does not return the maximal length of a string stored as JSON value -- it returns the maximal number of
string elements the JSON value can store which is `1`.

## Examples

??? example

    The following code calls `max_size()` on the different value types.
        
    ```cpp
    #include <iostream>
    #include <nlohmann/json.hpp>
    
    using json = nlohmann::json;
    
    int main()
    {
        // create JSON values
        json j_null;
        json j_boolean = true;
        json j_number_integer = 17;
        json j_number_float = 23.42;
        json j_object = {{"one", 1}, {"two", 2}};
        json j_array = {1, 2, 4, 8, 16};
        json j_string = "Hello, world";
    
        // call max_size()
        std::cout << j_null.max_size() << '\n';
        std::cout << j_boolean.max_size() << '\n';
        std::cout << j_number_integer.max_size() << '\n';
        std::cout << j_number_float.max_size() << '\n';
        std::cout << j_object.max_size() << '\n';
        std::cout << j_array.max_size() << '\n';
        std::cout << j_string.max_size() << '\n';
    }
    
    ```
    
    Output:
    
    ```json
    0
    1
    1
    1
    115292150460684697
    576460752303423487
    1
    
    ```

    Note the output is platform-dependent.

## See also

- [size](size.md) returns the number of elements
- [array_t](array_t.md) the type used to store JSON arrays
- [object_t](object_t.md) the type used to store JSON objects

## Version history

- Added in version 1.0.0.
- Extended to return `1` for binary types in version 3.8.0.