diff --git a/docs/empty.md b/docs/empty.md new file mode 100644 index 00000000..62f269be --- /dev/null +++ b/docs/empty.md @@ -0,0 +1,55 @@ +# nlohmann::basic_json::empty + +```cpp +bool empty() const noexcept; +``` + +Checks if the container has no elements; that is, whether `begin() == end()`. + +## Parameters + +(none) + +## Return value + +`true` if the container is empty, `false` otherwise. Note that the JSON types string, number, and boolean are never empty, null values are always empty. + +## Exceptions + +`noexcept` specification: `noexcept`. + +## Complexity + +Constant (assuming types `ObjectType` and `ArrayType` satisfy the [Container](http://en.cppreference.com/w/cpp/concept/Container) concept). + +## Example + +The following code uses empty to check if a `json` container contains any elements: + +```cpp +#include +#include + +int main() +{ + nlohman::json numbers; + std::cout << "Initially, numbers.empty(): " << numbers.empty() << '\n'; + + numbers.push_back(42); + numbers.push_back(13317); + std::cout << "After adding elements, numbers.empty(): " << numbers.empty() << '\n'; +} +``` + +### Output + + Initially, numbers.empty(): 1 + After adding elements, numbers.empty(): 0 + +## Requirements + +The `empty` member function is part of the [Container](http://en.cppreference.com/w/cpp/concept/Container) requirement. + +## See also + +- `size()` diff --git a/docs/index.md b/docs/index.md index 577c542f..e824bd05 100644 --- a/docs/index.md +++ b/docs/index.md @@ -108,7 +108,7 @@ using json = basic_json< ### Capacity -- `empty` +- [`empty`](empty) - `size` - `max_size`