Defined in header <utility>
template< class R, class T >
constexpr bool in_range( T t ) noexcept;
(since C++20)

Returns true if the value of t is in the range of values that can be represented in R, that is, if t can be converted to R without data loss.

It is a compile-time error if either T or R is not a signed or unsigned integer type (including standard integer type and extended integer type).


t - value to test

Return value

true if the value of t is representable in R, false otherwise.

Possible implementation

template<class R, class T>
constexpr bool in_range(T t) noexcept
    return std::cmp_greater_equal(t, std::numeric_limits<R>::min()) &&
        std::cmp_less_equal(t, std::numeric_limits<R>::max());


This function cannot be used with enums (including std::byte), char, char8_t, char16_t, char32_t, wchar_t and bool.

Feature-test macro Value Std Comment
__cpp_lib_integer_comparison_functions 202002L (C++20) Integer comparison functions


#include <iostream>
#include <utility>
int main()
    std::cout << std::boolalpha;
    std::cout << std::in_range<std::size_t>(-1) << '\n';
    std::cout << std::in_range<std::size_t>(42) << '\n';



See also

returns the smaller of the given values
returns the greater of the given values
clamps a value between a pair of boundary values
linear interpolation function

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