JSON for Modern C++  3.0
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 = int64_t, class NumberFloatType = double, template< typename U > class AllocatorType = std::allocator>
const_iterator nlohmann::basic_json::begin ( ) const
inlinenoexcept

Returns a const iterator to the first element.

range-begin-end.svg
Illustration from cppreference.com
Returns
const iterator to the first element
Complexity
Constant.
Requirements
This function satisfies the Container requirements:
  • The complexity is constant.
  • Has the semantics of const_cast<const basic_json&>(*this).begin().
Example
The following code shows an example for cbegin.
1 #include <json.hpp>
2 
3 using namespace nlohmann;
4 
5 int main()
6 {
7  // create an array value
8  const json array = {1, 2, 3, 4, 5};
9 
10  // get am iterator to the first element
11  json::const_iterator it = array.cbegin();
12 
13  // serialize the element that the iterator points to
14  std::cout << *it << '\n';
15 }
const_iterator cbegin() const noexcept
returns a const iterator to the first element
Definition: json.hpp:2692
a class to store JSON values
Definition: json.hpp:121
namespace for Niels Lohmann
Definition: json.hpp:56
a const random access iterator for the basic_json class
Definition: json.hpp:4497
Output:
1
The example code above can be translated with
g++ -std=c++11 -Isrc doc/examples/cbegin.cpp -o cbegin 
.