integer literal in C
An integer literal can be a decimal, octal, or hexadecimal constant. A prefix specifies the base or radix: 0x or 0X for hexadecimal, 0 for octal, and nothing for decimal. An integer literal can also have a suffix, * L or l: It is a size qualifier that specifies the size of the integer type as long. * U or u: It is a sign qualifier that represents the type of the integer as unsigned. An unsigned qualifier contains only positive values.