documented empty()

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Niels 2015-04-01 23:23:36 +02:00
parent 9767523924
commit 7db167afd1
2 changed files with 56 additions and 1 deletions

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docs/empty.md Normal file
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# 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 <json.hpp>
#include <iostream>
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()`

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### Capacity
- `empty`
- [`empty`](empty)
- `size`
- `max_size`