max_size - JSON for Modern C++ (original) (raw)

nlohmann::basic_json::max_size

size_type max_size() const noexcept;

Returns the maximum number of elements a JSON value is able to hold due to system or library implementation limitations, i.e. std::distance(begin(), end()) for the JSON value.

Return value

The return value depends on the different types and is defined as follows:

Value type return value
null 0 (same as size())
boolean 1 (same as size())
string 1 (same as size())
number 1 (same as size())
binary 1 (same as size())
object result of function object_t::max_size()
array result of function array_t::max_size()

Exception safety

No-throw guarantee: this function never throws exceptions.

Complexity

Constant, as long as array_t and object_t satisfy the Container concept; that is, their max_size() functions have constant complexity.

Notes

This function does not return the maximal length of a string stored as JSON value -- it returns the maximal number of string elements the JSON value can store which is 1.

Examples

Example

The following code calls max_size() on the different value types.

`#include #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_float = 23.42; json j_object = {{"one", 1}, {"two", 2}}; json j_array = {1, 2, 4, 8, 16}; json j_string = "Hello, world";

// call max_size()
std::cout << j_null.max_size() << '\n';
std::cout << j_boolean.max_size() << '\n';
std::cout << j_number_integer.max_size() << '\n';
std::cout << j_number_float.max_size() << '\n';
std::cout << j_object.max_size() << '\n';
std::cout << j_array.max_size() << '\n';
std::cout << j_string.max_size() << '\n';

} `

Output:

0 1 1 1 115292150460684697 576460752303423487 1

Note the output is platform-dependent.

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