ckd_add

Computes the addition x + y and stores the result into * result . The addition is performed as if both operands were represented in a signed integer type with infinite range, and the result was then converted from this integer type to type1 . If the value assigned to * result correctly represents the mathematical result of the operation, it returns false . Otherwise, it returns true . In this case, the value assigned to * result is the mathematical result of the operation wrapped around to the width of * result .

Parameters

Return value

false if the value assigned to * result correctly represents the mathematical result of the addition, true otherwise.

Note

The function template ckd_add has the same semantics as the corresponding type-generic macro with the same name specified in C23 .

Each of the types type1 , type2 , and type3 is a cv-unqualified signed or unsigned integer type.

It is recommended to produce a diagnostic message if type2 or type3 are not suitable integer types, or if * result is not a modifiable lvalue of a suitable integer type.

Example

#include <cstdint>
#include <limits>
#include <print>
#include <stdckdint.h>
int main()
{
    const std::uint8_t x{14};
    std::uint16_t y{28}, result1{};
    bool overflow{};
    overflow = ckd_add(&result1, x, y);
    std::println("{} + {} => {} ({})", x, y, result1, overflow ? "Overflow" : "OK");
    y = std::numeric_limits<std::uint16_t>::max();
    overflow = ckd_add(&result1, x, y);
    std::println("{} + {} => {} ({})", x, y, result1, overflow ? "Overflow" : "OK");
    std::uint32_t result2{};
    overflow = ckd_add(&result2, x, y);
    std::println("{} + {} => {} ({})", x, y, result2, overflow ? "Overflow" : "OK");
}

14 + 28 => 42 (OK)
14 + 65535 => 13 (Overflow)
14 + 65535 => 65549 (OK)

References

See also