Integers in C

Integers in C

Integer is written in C language as Int. Integers are whole numbers, which have no fractional part, or decimal point.

• They can be both positive and negative.
• Unsigned integers (positive values only) are supported.
• In addition, there are short and long integers.
• Examples of integers include:
  • 0   57   4567   128933
• The keyword used to define integers is: int
• Integer variables are declared using:
  • int variable_name;
  • For example: int a;

Long Integers

Sometimes extra digits are needed to store numbers larger than those allowed in a normal int and it is declared as long int variable_name.

The long qualifier informs C that extra storage is required for the integer. Long integers are normally in the range

-2³¹… 2³¹-1 or -2147483648…2147483647

Short Integers

Sometimes less digits are needed to store a number such as

short int variable_name;

The short qualifier informs C that less storage is required for the integer and Short integers are normally in the range:

  -2¹⁵… 2₁₅-1 or -32768..32767

Unsigned Integers

Unsigned integers contain positive values only

• An integer with n bits uses n bits for the number
• An integer with n bits → 2ⁿ integers in the range [0,2ⁿ-1]
  •   e.g. if n=16 → 65536 integers, 0..65535
• Unsigned integers are declared:
  • unsigned int variable_name;
  •   unsigned short variable_name;
  •   unsigned long variable_name;

Signed Integers

Signed integers allow both positive and negative values

• An integer with n bits uses n-1 bits for the number and 1 bit for the sign
  • (+ve = 0, -ve = 1)
• 2ⁿ integers in the range [-(2^n-1),(2^n-1-1)]
  •     e.g. n=16 → 65536 integers, -322768..32767
• All int declarations default to signed
• Signed integers are declared:
  • signed int variable_name;
• which is equivalent to:  int variable_name;

Integers in C On a 16-bit System

Type	Approximate Range
short	-32768..32767
unsigned short	0..65535
int	-32768..32767
unsigned int	0..65535
long	-2147483648..2147483647
unsigned long	0..4294967295

A note on Integers/ints

Suffixes can be appended to an integer constant to specify its type. Can be used with int, long, or unsigned long

Example	Type	Suffix
u or U	unsigned	37U
l or L	long	37L
ul or UL	unsigned long	37UL