Input - Output in C

The input - output is performed through set of library functions , that are supplied with every C compiler. If a program uses any function from standard input /output library, then it should include the header file <stdio.h> .

Conversion specification character : scanf() and printf()  make use of conversion specification character to specify the the type and size of data . It must begin with % .

Ex.          %d  for integer

                %c  for single character constant

                %s  for string

Reading input data :

scanf( ) library function

scanf( " Control String", address 1, address 2, ..... ,address n);

scanf() should have at least two parameters :- 1) Control string    2) Address . Control string contains conversion specification character . It should be written within double quotes. Conversion specification character may be one or more . It depends on number of values we want to input but at least one address should be present. Address of variable is found by preceding the variable by an  & sign. & is address of operator which gives starting address of variable name in memory. It should be noted that a sting variable is not preceded by an &.

 void main( )

{

int z;

..........

scanf( " %d", &z); 

..........................

..........................

}

Writing output  data :

printf( ) library function

printf( " Control String", variable 1, variable 2, ..... ,variable n);

Control string contains conversion specification character or text or both. If the control string does not contain any conversion specification,then variable names are not specified . The name of variable should not be preceded by an & sign.

#include <stdio.h>

void main( )

{

int a;

printf("Enter Number :  \n");

scanf( "%d", &a);

printf(" Number = %d",a);

}