ckd_add

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros(C++20)

Language support library

Concepts library(C++20)

Diagnostics library

Memory management library

Metaprogramming library(C++11)

General utilities library

Containers library

Iterators library

Ranges library(C++20)

Algorithms library

Strings library

Text processing library

Numerics library

Date and time library

Input/output library

Filesystem library(C++17)

Concurrency support library(C++11)

Execution control library(C++26)

Technical specifications

Symbols index

External libraries

 

Numerics library

Common mathematical functions
Mathematical special functions(C++17)
Mathematical constants(C++20)
Basic linear algebra algorithms(C++26)
Data-parallel types (SIMD)(C++26)
Floating-point environment(C++11)
Complex numbers
Numeric array (valarray)
Pseudo-random number generation
Bit manipulation(C++20)
Saturation arithmetic(C++26)
Factor operations
gcd (C++17)	lcm (C++17)
Interpolations
midpoint (C++20)	lerp (C++20)
Generic numeric operations
iota (C++11) ranges::iota (C++23) accumulate inner_product adjacent_difference    partial_sum	reduce (C++17) transform_reduce (C++17) inclusive_scan (C++17) exclusive_scan (C++17) transform_inclusive_scan (C++17) transform_exclusive_scan (C++17)
C-style checked integer arithmetic
ckd_add (C++26) ckd_sub (C++26)	ckd_mul (C++26)

 

Defined in header <stdckdint.h>
template<class type1, class type2, class type3 > bool ckd_add( type1* result, type2 a, type3 b );		(since C++26)

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

a, b	-	integer values
result	-	address of where result should be stored

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

Compiler Explorer preview.

Run this code

#include <cstdint>#include <limits>#include <print>#include <stdckdint.h>   int main(){conststd::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");}

Possible output:

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

References

• C++26 standard (ISO/IEC 14882:2026):

• 29.11.2 Checked integer operations

See also

ckd_sub (C++26)	checked subtraction operation on two integers (function template)
ckd_mul (C++26)	checked multiplication operation on two integers (function template)
C documentation for ckd_add