42 lines
1.4 KiB
Markdown
42 lines
1.4 KiB
Markdown
|
```cpp
|
|||
|
|
iterator begin();
|
|||
|
|
const_iterator begin() const;
|
|||
|
|
const_iterator cbegin() const;
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
## Description
|
|||
|
|
|
|||
|
|
Returns an iterator to the first value in the JSON container. If the JSON container is empty, the returned iterator will be equal to [`end()`](https://github.com/nlohmann/json/wiki/nlohmann::basicjson::end).
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
## Parameters
|
|||
|
|
|
|||
|
|
None.
|
|||
|
|
|
|||
|
|
## Return value
|
|||
|
|
|
|||
|
|
Iterator to the first value. Note the return value its deferencabilty depends on the different value types:
|
|||
|
|
|
|||
|
|
| value type | deferenceable | description |
|
|||
|
|
| ---------- | ------------- | ----------- |
|
|||
|
|
| null | no | `null` has no value, always equal to [`end()`](https://github.com/nlohmann/json/wiki/nlohmann::basicjson::end) |
|
|||
|
|
| boolean | yes | iterator to the boolean value |
|
|||
|
|
| string | yes | iterator to the string value |
|
|||
|
|
| number | yes | iterator to the number value |
|
|||
|
|
| object | only if object is not empty | iterator to the begin of the object |
|
|||
|
|
| array | only if array is not empty | iterator to the begin of the array |
|
|||
|
|
|
|||
|
|
## Complexity
|
|||
|
|
|
|||
|
|
Constant, as long as `ArrayType` and `ObjectType` satisfy the [Container concept](http://en.cppreference.com/w/cpp/concept/Container).
|
|||
|
|
|
|||
|
|
## Exceptions
|
|||
|
|
|
|||
|
|
None. The function's noexcept-specification is `noexcept`.
|
|||
|
|
|
|||
|
|
## See also
|
|||
|
|
|
|||
|
|
- [**end**, **cend**](https://github.com/nlohmann/json/wiki/nlohmann::basicjson::end)<br>
|
|||
|
|
returns an iterator to the end
|