Integers, long and short in C

Turbo C or Turbo C++ the range is –32768 to 32767. For a 32-bit compiler the range would be –2147483648 to +2147483647. Here a 16-bit compiler means that when it compiles a C program it generates machine language code that is targeted towards working on a 16-bit microprocessor like Intel 8086/8088. As against this, a 32-bit compiler like VC++ generates machine language code that is targeted towards a 32-bit microprocessor like Intel Pentium. Note that this does not mean that a program compiled using Turbo C would not work on 32-bit processor. It would run successfully but at that time the 32-bit processor would work as if it were a 16-bit processor. This happens because a 32-bit processor provides support for programs compiled using 16-bit compilers. If this backward compatibility support is not provided the 16-bit program

would not run on it. This is precisely what happens on the new Intel Itanium processors, which have withdrawn support for 16-bit code

Remember that out of the two/four bytes used to store an integer, the highest bit (16th/32nd bit) is used to store the sign of the integer. This bit is 1 if the number is negative, and 0 if the number is positive.

C offers a variation of the integer data type that provides what are called short and long integer values. The intention of providing these variations is to provide integers with different ranges wherever possible. Though not a rule, short and long integers would usually occupy two and four bytes respectively. Each compiler can decide appropriate sizes depending on the operating system and hardware for which it is being written, subject to the following rules:

• shorts are at least 2 bytes big
• longs are at least 4 bytes big
• shorts are never bigger than ints
• ints are never bigger than longs

Sizes of different integers based upon the OS used