[Solved] Unsigned int not working C++

Question

You are expecting the cast from int to unsigned int to simply change the sign of a negative value while maintaining its magnitude. But that isn’t how it works in C or C++. when it comes to overflow, unsigned integers follow modular arithmetic, meaning that assigning or initializing from negatives values such as -1 or -2 wraps around to the largest and second largest unsigned values, and so on. So, for example, these two are equivalent:

unsigned int n = -1;
unsigned int m = -2;

and

unsigned int n = std::numeric_limits<unsigned int>::max();
unsigned int m = std::numeric_limits<unsigned int>::max() - 1;

See this working example.

Also note that there is no substantial difference between programs 1 and 2. It is all down to the sign of the value used to initialize or assign to the unsigned integer.

Accepted Answer

You are expecting the cast from int to unsigned int to simply change the sign of a negative value while maintaining its magnitude. But that isn’t how it works in C or C++. when it comes to overflow, unsigned integers follow modular arithmetic, meaning that assigning or initializing from negatives values such as -1 or -2 wraps around to the largest and second largest unsigned values, and so on. So, for example, these two are equivalent:

unsigned int n = -1;
unsigned int m = -2;

and

unsigned int n = std::numeric_limits<unsigned int>::max();
unsigned int m = std::numeric_limits<unsigned int>::max() - 1;

See this working example.

Also note that there is no substantial difference between programs 1 and 2. It is all down to the sign of the value used to initialize or assign to the unsigned integer.