In C each variable has a type as well as a value:
- The type determines the meaning of the operations that can be applied to the value
- For example, declarations like
int i, j; double d; float x;
determine the operations and space requirements of the variables. The data type of every variable in a C program must be declared before that variable can appear in a statement.
There are four basic data types in C:
char – a single byte, capable of holding one character int – an integer float – single-precision floating point double – double precision floating point
There is NO (true/false) type in C, the conditions true and false are represented by the integer values 1 and 0, respectively.
Sizes of data types On a 16-bit System
C Type | Size (bits) | Size (Byte) | Format Pacifiers |
char | 8 | 1 | %c |
unsigned char | 8 | 1 | %u |
int | 16 | 2 | %d |
short int | 16 | 2 | %d |
long int | 32 | 4 | %ld |
float | 32 | 4 | %f |
double | 64 | 8 | %lf |
long double | 80 | 10 | %Lf |
Example 1: Integer in C
#include <stdio.h> #include <stdlib.h> int main(int argc, char *argv[]) { int a; int c; int b; a=10; b=20; c=a+b; printf("The sum is %d",c); return 0; }
Output:
The sum is 30
Example 2: Character in C
#include <stdio.h> #include <stdlib.h> int main(int argc, char *argv[]) { char ch; ch='A'; printf("Character is %c ",ch); printf("\n"); printf("ASCII code for character %c is %d",ch,ch); return 0; }
Output:
Character is A
ASCII code for character A is 65
Example 3: Checking either the character is Capital or Small in C
#include <stdio.h> #include <stdlib.h> /* run this program using the console pauser or add your own getch, system("pause") or input loop */ int main(int argc, char *argv[]) { char ch; printf("Enter your favourite character: "); ch=getche(); printf("\n"); printf("Your Favourite character is %c",ch); if(ch>=65 && ch<=91) printf("\nIt is Capital Letter"); else if(ch>=97 && ch<=122) printf("\nIt is Small Letter"); return 0; }
Output:

Example 4: Using float data type in C
#include <stdio.h> #include <stdlib.h> /* run this program using the console pauser or add your own getch, system("pause") or input loop */ int main(int argc, char *argv[]) { float pi=3.1416; float r,a; printf("Enter radius of a circle: "); scanf("%f",&r); a=pi*r*r; printf("\n"); printf("Area of a circle is %f",a); }
Output:

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