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>
template<class CompatibleObjectType , typename std::enable_if< std::is_constructible< typename object_t::key_type, typename CompatibleObjectType::key_type >::value andstd::is_constructible< basic_json, typename CompatibleObjectType::mapped_type >::value, int >::type = 0>
nlohmann::basic_json::basic_json ( const CompatibleObjectType &  value)
inline

Create an object JSON value with a given content. This constructor allows any type that can be used to construct values of type object_t. Examples include the types std::map and std::unordered_map.

Template Parameters
CompatibleObjectTypean object type whose key_type and value_type is compatible to object_t
Parameters
[in]valuea value for the object
Complexity
Linear in the size of the passed value.
Exceptions
std::bad_allocif allocation for object value fails
Example
The following code shows the constructor with several compatible object type parameters.
1 #include <json.hpp>
2 #include <unordered_map>
3 
4 using namespace nlohmann;
5 
6 int main()
7 {
8  // create an object from std::map
9  std::map<std::string, int> c_map
10  {
11  {"one", 1}, {"two", 2}, {"three", 3}
12  };
13  json j_map(c_map);
14 
15  // create an object from std::unordered_map
16  std::unordered_map<const char*, double> c_umap
17  {
18  {"one", 1.2}, {"two", 2.3}, {"three", 3.4}
19  };
20  json j_umap(c_umap);
21 
22  // create an object from std::multimap
23  std::multimap<std::string, bool> c_mmap
24  {
25  {"one", true}, {"two", true}, {"three", false}, {"three", true}
26  };
27  json j_mmap(c_mmap); // only one entry for key "three" is used
28 
29  // create an object from std::unordered_multimap
30  std::unordered_multimap<std::string, bool> c_ummap
31  {
32  {"one", true}, {"two", true}, {"three", false}, {"three", true}
33  };
34  json j_ummap(c_ummap); // only one entry for key "three" is used
35 
36  // serialize the JSON objects
37  std::cout << j_map << '\n';
38  std::cout << j_umap << '\n';
39  std::cout << j_mmap << '\n';
40  std::cout << j_ummap << '\n';
41 }
a class to store JSON values
Definition: json.hpp:130
namespace for Niels Lohmann
Definition: json.hpp:55
Output (play with this example online):
{"one":1,"three":3,"two":2}
{"one":1.2,"three":3.4,"two":2.3}
{"one":true,"three":false,"two":true}
{"one":true,"three":false,"two":true}
The example code above can be translated with
g++ -std=c++11 -Isrc doc/examples/basic_json__CompatibleObjectType.cpp -o basic_json__CompatibleObjectType 
See also
basic_json(const object_t&)