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◆ type()
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, class BinaryType = std::vector<std::uint8_t>>
constexpr value_t nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::type |
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Return the type of the JSON value as a value from the value_t enumeration.
- Returns
- the type of the JSON value
Value type | return value |
null | value_t::null |
boolean | value_t::boolean |
string | value_t::string |
number (integer) | value_t::number_integer |
number (unsigned integer) | value_t::number_unsigned |
number (floating-point) | value_t::number_float |
object | value_t::object |
array | value_t::array |
binary | value_t::binary |
discarded | value_t::discarded |
- Complexity^^ Constant.
- Exception safety^^ No-throw guarantee: this member function never throws
- exceptions.
- Example^^ The following code exemplifies type() for all JSON
- types. ^^
2 #include <nlohmann/json.hpp> 10 json j_boolean = true; 11 json j_number_integer = -17; 12 json j_number_unsigned = 42u; 13 json j_number_float = 23.42; 14 json j_object = {{ "one", 1}, { "two", 2}}; 15 json j_array = {1, 2, 4, 8, 16}; 16 json j_string = "Hello, world"; 19 std::cout << std::boolalpha; 20 std::cout << (j_null.type() == json::value_t::null) << '\n'; 21 std::cout << (j_boolean.type() == json::value_t::boolean) << '\n'; 22 std::cout << (j_number_integer.type() == json::value_t::number_integer) << '\n'; 23 std::cout << (j_number_unsigned.type() == json::value_t::number_unsigned) << '\n'; 24 std::cout << (j_number_float.type() == json::value_t::number_float) << '\n'; 25 std::cout << (j_object.type() == json::value_t::object) << '\n'; 26 std::cout << (j_array.type() == json::value_t::array) << '\n'; 27 std::cout << (j_string.type() == json::value_t::string) << '\n'; basic_json<> json default JSON class
Output (play with this example online):^^ true
true
true
true
true
true
true
true
^^ The example code above can be translated withg++ -std=c++11 -Isingle_include doc/examples/type.cpp -o type
- See also
- operator value_t() – return the type of the JSON value (implicit)
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type_name() – return the type as string
- Since
- version 1.0.0
Definition at line 18812 of file json.hpp.
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