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67 lines
1.7 KiB
Markdown
67 lines
1.7 KiB
Markdown
# nlohmann::basic_json::begin
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```
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iterator begin() noexcept;
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const_iterator begin() const noexcept;
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```
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Returns an iterator to the first element.
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`begin()` points to the first element and `end()` to the position after the last element; the dashed cell is the past-the-last position, which must not be dereferenced.
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## Return value
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iterator to the first element
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## Exception safety
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No-throw guarantee: this member function never throws exceptions.
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## Complexity
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Constant.
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## Examples
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Example
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The following code shows an example for `begin()`.
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```
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#include <iostream>
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#include <nlohmann/json.hpp>
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using nlohmann::json;
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int main()
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{
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// create an array value
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json array = {1, 2, 3, 4, 5};
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// get an iterator to the first element
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json::iterator it = array.begin();
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// serialize the element that the iterator points to
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std::cout << *it << '\n';
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}
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```
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Output:
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```
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1
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```
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## See also
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- [`end`](https://json.nlohmann.me/api/basic_json/end/index.md) - returns an iterator to one past the last element
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- [`cbegin`](https://json.nlohmann.me/api/basic_json/cbegin/index.md) - returns a const iterator to the first element
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- [`rbegin`](https://json.nlohmann.me/api/basic_json/rbegin/index.md) - returns a reverse iterator to the last element
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- [`items`](https://json.nlohmann.me/api/basic_json/items/index.md) - returns an iteration proxy to access keys and values during range-based for loops
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- [Iterators](https://json.nlohmann.me/features/iterators/index.md) - the article on iterators
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- [`basic_json_view::begin`](https://json.nlohmann.me/api/basic_json_view/begin/index.md) - the same iteration on a zero-copy view (in document order, not sorted by key)
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## Version history
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- Added in version 1.0.0.
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