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◆ is_array()
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 bool nlohmann::basic_json< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer, BinaryType >::is_array |
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This function returns true if and only if the JSON value is an array.
- Returns
true if type is array, false otherwise.
- Complexity
- Constant.
- Exception safety
- No-throw guarantee: this member function never throws exceptions.
- Example
- The following code exemplifies
is_array() 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_integer = 12345678987654321u;
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";
20 std::cout << std::boolalpha;
21 std::cout << j_null. is_array() << '\n';
22 std::cout << j_boolean.is_array() << '\n';
23 std::cout << j_number_integer.is_array() << '\n';
24 std::cout << j_number_unsigned_integer.is_array() << '\n';
25 std::cout << j_number_float.is_array() << '\n';
26 std::cout << j_object.is_array() << '\n';
27 std::cout << j_array.is_array() << '\n';
28 std::cout << j_string.is_array() << '\n';
29 std::cout << j_binary.is_array() << '\n';
Output (play with this example online): false
false
false
false
false
false
true
false
false
The example code above can be translated withg++ -std=c++11 -Isingle_include doc/examples/is_array.cpp -o is_array
- Since
- version 1.0.0
Definition at line 19073 of file json.hpp.
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