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nlohmann::basic_json::is_array

constexpr bool is_array() const noexcept;

This function returns true if and only if the JSON value is an array.

Return value

true if type is an array, false otherwise.

Exception safety

No-throw guarantee: this member function never throws exceptions.

Complexity

Constant.

Examples

Example

The following code exemplifies is_array() for all JSON types.

#include <iostream> #include <nlohmann/json.hpp> using json = nlohmann::json; int main() {  // create JSON values  json j_null;  json j_boolean = true;  json j_number_integer = 17;  json j_number_unsigned_integer = 12345678987654321u;  json j_number_float = 23.42;  json j_object = {{"one", 1}, {"two", 2}};  json j_array = {1, 2, 4, 8, 16};  json j_string = "Hello, world";  json j_binary = json::binary({1, 2, 3});  // call is_array()  std::cout << std::boolalpha;  std::cout << j_null.is_array() << '\n';  std::cout << j_boolean.is_array() << '\n';  std::cout << j_number_integer.is_array() << '\n';  std::cout << j_number_unsigned_integer.is_array() << '\n';  std::cout << j_number_float.is_array() << '\n';  std::cout << j_object.is_array() << '\n';  std::cout << j_array.is_array() << '\n';  std::cout << j_string.is_array() << '\n';  std::cout << j_binary.is_array() << '\n'; }

Output:

false false false false false false true false false

Version history

  • Added in version 1.0.0.