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
-2^{31}… 2^{31}-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:
-2^{15}… 2_{15}-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 → 2^{n} integers in the range [0,2^{n}-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)
- 2^{n} 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 |
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