JSON for Modern C++  2.0.0
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 NumberUnsignedType = uint64_t, class NumberFloatType = double, template< typename U > class AllocatorType = std::allocator>
const_reference nlohmann::basic_json::operator[] ( size_type  idx) const
inline

Returns a const reference to the element at specified location idx.

Parameters
[in]idxindex of the element to access
Returns
const reference to the element at index idx
Exceptions
std::domain_errorif JSON is not an array; example: "cannot use operator[] with null"
Complexity
Constant.
Example
The example below shows how array elements can be read using the [] operator.
1 #include <json.hpp>
2 
3 using json = nlohmann::json;
4 
5 int main()
6 {
7  // create JSON array
8  json array = {"first", "2nd", "third", "fourth"};
9 
10  // output element at index 2 (third element)
11  std::cout << array.at(2) << '\n';
12 }
basic_json<> json
default JSON class
Definition: json.hpp:8653
Output (play with this example online):
"third"
The example code above can be translated with
g++ -std=c++11 -Isrc doc/examples/operatorarray__size_type_const.cpp -o operatorarray__size_type_const 
Since
version 1.0.0

Definition at line 3234 of file json.hpp.