mirror of
https://github.com/nlohmann/json
synced 2024-11-24 04:40:13 +00:00
42 lines
1.4 KiB
Markdown
42 lines
1.4 KiB
Markdown
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```cpp
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iterator begin();
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const_iterator begin() const;
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const_iterator cbegin() const;
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```
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## Description
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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).
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## Parameters
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None.
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## Return value
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Iterator to the first value. Note the return value its deferencabilty depends on the different value types:
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| value type | deferenceable | description |
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| ---------- | ------------- | ----------- |
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| null | no | `null` has no value, always equal to [`end()`](https://github.com/nlohmann/json/wiki/nlohmann::basicjson::end) |
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| boolean | yes | iterator to the boolean value |
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| string | yes | iterator to the string value |
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| number | yes | iterator to the number value |
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| object | only if object is not empty | iterator to the begin of the object |
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| array | only if array is not empty | iterator to the begin of the array |
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## Complexity
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Constant, as long as `ArrayType` and `ObjectType` satisfy the [Container concept](http://en.cppreference.com/w/cpp/concept/Container).
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## Exceptions
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None. The function's noexcept-specification is `noexcept`.
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## See also
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- [**end**, **cend**](https://github.com/nlohmann/json/wiki/nlohmann::basicjson::end)<br>
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returns an iterator to the end
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