# Integer overflow Detects overflow in arithmetic. ## Overview Overflows result in undefined behavior. Use this check to detect overflows in addition, subtraction, multiplication, and division. Available in Xcode 9 and later. ### Signed addition overflow in C In the following code, the `x` variable has the maximum `int32_t` value before the addition, and the result of the addition overflows `x`, which the optimizer may not handle in a predictable way: ```occ int32_t x = (1U << 31) - 1; x += 1; // Error: the add result can't fit in x ``` > Note: With the exception of the signed division check, enabling the `-fwrapv` compiler flag disables UBSan overflow checks. #### Solution One way to address signed overflow is to use larger types. If you don’t need to represent negative numbers, another option is to use unsigned types, which wrap on arithmetic overflow. Alternatively, pass the `-fwrapv` flag to the compiler to enable signed wraparound on overflow. However, this may adversely impact performance. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)