How do I store a negative integer in C?

13 down vote Passing %d to printf tells printf to treat the argument as a signed integer, regardless of what you actually pass. Use %u to print as unsigned. 6 down vote It all has to do with interpretation of the value. If you assume 16 bit signed and unsigned integers, then here some examples that aren't exactly correct, but demonstrate the concept. 0000 0000 0000 1100 unsigned int, and signed int value 12 1000 0000 0000 1100 signed int value -12, and a large unsigned integer. For signed integers, the bit on the left is the sign bit. 0 = positive 1 = negative For unsigned integers, there is no sign bit. the left hand bit, lets you store a larger number instead. So the reason you are not seeing what you are expecting is that. unsigned int x = -12, takes -12 as an integer, and stores it into x. x is unsigned, so what was a sign bit, is now a piece of the value. printf lets you tell the compiler how you want a value to be displayed. %d means display it as if it were a signed int. %u means display it as if it were an unsigned int. c lets you do this kind of stuff. You the programmer are in control. Kind of like a firearm. It's a tool. You can use it correctly to deal with certain situations, or incorrectly to remove one of your toes. one possibly useful case is the following unsigned int allBitsOn = -1; That particular value sets all of the bits to 1 1111 1111 1111 1111 that can be useful sometimes. read less