JSON for Modern C++ 3.0

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basic_json
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basic_json
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basic_json
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~basic_json
| 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_reference nlohmann::basic_json::front | ( |  | ) | const
| inline
  Returns a reference to the first element in the container. For a JSON container `c`, the expression `c.front()` is equivalent to `*c.begin()`. Returns In case of a structured type (array or object), a reference to the first element is returned. In cast of number, string, or boolean values, a reference to the value is returned. Complexity Constant. Note Calling `front` on an empty container is undefined. Exceptions
  std::out_of_range | when called on null value
  Example The following code shows an example for front. 1 #include <json.hpp> 2 3 using namespace nlohmann; 4 5 int main() 6 { 7 // create JSON values 8 json j_null; 9 json j_boolean = true; 10 json j_number_integer = 17; 11 json j_number_float = 23.42; 12 json j_object = {{"one", 1}, {"two", 2}}; 13 json j_object_empty(json::value_t::object); 14 json j_array = {1, 2, 4, 8, 16}; 15 json j_array_empty(json::value_t::array); 16 json j_string = "Hello, world"; 17 18 // call front() 19 //std::cout << j_null.front() << '\n'; // would throw 20 std::cout << j_boolean.front() << '\n'; 21 std::cout << j_number_integer.front() << '\n'; 22 std::cout << j_number_float.front() << '\n'; 23 std::cout << j_object.front() << '\n'; 24 //std::cout << j_object_empty.front() << '\n'; // would throw 25 std::cout << j_array.front() << '\n'; 26 //std::cout << j_array_empty.front() << '\n'; // would throw 27 std::cout << j_string.front() << '\n'; 28 } nlohmann::basic_json a class to store JSON values Definition: json.hpp:121 nlohmann::basic_json::front reference front() access the first element Definition: json.hpp:2395 nlohmann::basic_json::value_t::object object (unordered set of name/value pairs) nlohmann namespace for Niels Lohmann Definition: json.hpp:56 nlohmann::basic_json::value_t::array array (ordered collection of values) Output:
      true
      17
      23.42
      1
      1
      "Hello, world"
  The example code above can be translated with
      g++ -std=c++11 -Isrc doc/examples/front.cpp -o front
.