How does unsigned integer overflow behave in C/C ?

Understanding Unsigned Integer Overflow in C/C

When working with integers, it's essential to consider the potential for arithmetic overflow. In C/C , integer overflow occurs when the result of a calculation exceeds the maximum or minimum value that can be represented by the integer data type.

For signed integers, overflow leads to undefined behavior, potentially causing errors or crashes. However, for unsigned integers, the behavior is different.

As stated in the provided article:

"A computation involving unsigned operands can never overflow, because a result that cannot be represented by the resulting unsigned integer type is reduced modulo to the number that is one greater than the largest value that can be represented by the resulting type."

This means that when an unsigned integer operation results in a value that exceeds its maximum representable value, it "wraps around" to the minimum value. For instance, if you add 1 to the maximum unsigned integer value (UINT_MAX), the result will be 0. This continues for subsequent additions, as illustrated by the following code:

printf("%u\n", UINT_MAX + 1); // prints 0
printf("%u\n", UINT_MAX + 2); // prints 1
printf("%u\n", UINT_MAX + 3); // prints 2

This wrapping-around behavior is similar to the modulo operation. When calculating the remainder of dividing a number by a constant, the result "wraps around" to the range [0, constant-1]. In the case of unsigned integer overflow, the constant is one greater than the maximum integer value of the resulting type.

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