JSON for Modern C++ 3.10.4

◆ begin() [2/2]

template<template< typename U, typename V, typename... Args > class ObjectType = std::map, template< typename U, typename... Args > class ArrayType = std::vector, class StringType = std::string, class BooleanType = bool, class NumberIntegerType = std::int64_t, class NumberUnsignedType = std::uint64_t, class NumberFloatType = double, template< typename U > class AllocatorType = std::allocator, template< typename T, typename SFINAE=void > class JSONSerializer = adl_serializer, class BinaryType = std::vector<std::uint8_t>>
iterator nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::begin ( )
inlinenoexcept

Returns an iterator to the first element.

Illustration from cppreference.com
Returns
iterator to the first element
Complexity
Constant.
Requirements
This function helps basic_json satisfying the Container requirements:
  • The complexity is constant.
Example
The following code shows an example for begin().
1#include <iostream>
2#include <nlohmann/json.hpp>
3
4using json = nlohmann::json;
5
6int main()
7{
8 // create an array value
9 json array = {1, 2, 3, 4, 5};
10
11 // get an iterator to the first element
12 json::iterator it = array.begin();
13
14 // serialize the element that the iterator points to
15 std::cout << *it << '\n';
16}
iter_impl< basic_json > iterator
an iterator for a basic_json container
Definition: json.hpp:17809
basic_json<> json
default JSON class
Definition: json.hpp:3472

Output (play with this example online):
1
The example code above can be translated with
g++ -std=c++11 -Isingle_include doc/examples/begin.cpp -o begin 
See also
see cbegin() – returns a const iterator to the beginning
see end() – returns an iterator to the end
see cend() – returns a const iterator to the end
Since
version 1.0.0

Definition at line 22191 of file json.hpp.