C9X adds two new types in response to technology growth. Also, it increases support for type portability. That is, it offers portable ways to deal with, say, int being different sizes on different platforms.
C9X adds the long long and unsigned long long types to the C language. As 64-bit processors begin to move into the mainstream and as storage devices with larger capacities become available, the long type, with its guaranteed 32-bit minimum capacity, may no longer be adequate. The long long and unsigned long long types have the means to store 64-bit values.
Extended Integers: Portable Types
Suppose you have a program that needs a 32-bit integer type. On some systems, int will work, but on others, it won't. The long type is ...