1# basic_json::count 2 3```cpp 4template<typename KeyT> 5size_type count(KeyT&& key) const; 6``` 7 8Returns the number of elements with key `key`. If `ObjectType` is the default `std::map` type, the return value will 9always be `0` (`key` was not found) or `1` (`key` was found). 10 11## Template parameters 12 13`KeyT` 14: A type for an object key. 15 16## Parameters 17 18`key` (in) 19: key value of the element to count. 20 21## Return value 22 23Number of elements with key `key`. If the JSON value is not an object, the return value will be `0`. 24 25## Exception safety 26 27Strong exception safety: if an exception occurs, the original value stays intact. 28 29## Complexity 30 31Logarithmic in the size of the JSON object. 32 33## Notes 34 35This method always returns `0` when executed on a JSON type that is not an object. 36 37## Example 38 39??? example 40 41 The example shows how `count()` is used. 42 43 ```cpp 44 --8<-- "examples/count.cpp" 45 ``` 46 47 Output: 48 49 ```json 50 --8<-- "examples/count.output" 51 ``` 52 53## Version history 54 55- Added in version 1.0.0. 56