Tuesday, September 24, 2013

INPUT AND OUTPUT OPERATIONS

INPUT AND OUTPUT OPERATIONS

ANSI standard has defined many library functions for input and output in C language.

 printf() and scanf() are the most commonly used to display output and take input respectively.

Let us consider an example:

#include <stdio.h>      //This is needed to run printf() function.
int main()
{
    printf("My course  BCA");  //displays the content inside quotation
    return 0;
}

Output
My course BCA

In the above program


printf() is a library function to display output which only works if #include<stdio.h>is included at the beginning.

Here, stdio.h is a standard input output header file .

 #include is command to paste the code from the header file whenever necessary.

When compiler encounters printf() function and doesn't find stdio.h header file, compiler shows error.

I/O of integers in C

#include<stdio.h>
int main()
{
    int c=5;
    printf()("Number=%d",c);
    return 0;
}
Output
Number=5

Inside quotation of printf() there, is a conversion format string "%d" (for integer). If this conversion format string matches with remaining argument,i.e, c in this case, value of c is displayed.

#include<stdio.h>
int main()
{
    int c;
    printf()("Enter a number\n");
    scanf()("%d",&c);
    printf()("Number=%d",c);
    return 0;
}
Output
Enter a number
4
Number=4

The scanf() function is used to take input from user.

In this program, the user is asked a input and value is stored in variable c.

Note the '&' sign before c. &c denotes the address of c and value is stored in that address.

Programming  In c is easy you should store your values in variables, then later perform  various  operations  on them and finally display the values from  the  variables.

Try various programs by changing data  types  and format specifiers.

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