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◆ operator+=() [4/4]
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>
add an object to an object This function allows to use push_back with an initializer list. In case
- the current value is an object,
- the initializer list init contains only two elements, and
- the first element of init is a string,
init is converted into an object element and added using push_back(const typename object_t::value_type&). Otherwise, init is converted to a JSON value and added using push_back(basic_json&&).
- Parameters
-
[in] | init | an initializer list |
- Complexity^^ Linear in the size of the initializer list init.
- Note
- This function is required to resolve an ambiguous overload error, because pairs like
{"key", "value"} can be both interpreted as object_t::value_type or std::initializer_list<basic_json> , see https://github.com/nlohmann/json/issues/235 for more information.
- Example^^ The example shows how initializer lists are treated as
- objects when possible. ^^
2 #include <nlohmann/json.hpp> 9 json object = {{ "one", 1}, { "two", 2}}; 13 std::cout << object << '\n'; 14 std::cout << null << '\n'; 17 object.push_back({ "three", 3}); 18 object += { "four", 4}; 19 null.push_back({ "five", 5}); 22 std::cout << object << '\n'; 23 std::cout << null << '\n'; basic_json<> json default JSON class
Output (play with this example online):^^ {"one":1,"two":2}
null
{"four":4,"one":1,"three":3,"two":2}
[["five",5]]
^^ The example code above can be translated withg++ -std=c++11 -Isingle_include doc/examples/push_back__initializer_list.cpp -o push_back__initializer_list
Definition at line 17277 of file json.hpp.
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