json/api/basic_json/max_size.md

nlohmann::basic_json::max_size

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())
boolean	1 (same as size())
string	1 (same as size())
number	1 (same as size())
binary	1 (same as size())
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 and object_t satisfy the 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
--8<-- "examples/max_size.cpp"
```

Output:

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

Note the output is platform-dependent.

Version history

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