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1.0 KiB
1.0 KiB
nlohmann::basic_json::count
template<typename KeyT>
size_type count(KeyT&& key) const;
Returns the number of elements with key key. If ObjectType is the default std::map type, the return value will
always be 0 (key was not found) or 1 (key was found).
Template parameters
KeyT- A type for an object key.
Parameters
key(in)- key value of the element to count.
Return value
Number of elements with key key. If the JSON value is not an object, the return value will be 0.
Exception safety
Strong exception safety: if an exception occurs, the original value stays intact.
Complexity
Logarithmic in the size of the JSON object.
Notes
This method always returns 0 when executed on a JSON type that is not an object.
Examples
??? example
The example shows how `count()` is used.
```cpp
--8<-- "examples/count.cpp"
```
Output:
```json
--8<-- "examples/count.output"
```
Version history
- Added in version 1.0.0.