Input & Output Functions in 'C'

Input means to provide the program with some data to be used in the program
Output means to display data on screen or write the data to a printer or a file.
C programming language provides many built-in functions to read any given input and to display data on screen when there is a need to output the result.
In this tutorial, we will learn about such functions, which can be used in our program to take input from user and to output the result on screen.
All these built-in functions are present in C header file "#include<stdio.h>"
To use the built in functions we have to specify header files at head in which a particular function is defined(written) while discussing about it.

printf() & scanf()

printf() Function

"This Function is used to print formatted data from the keyboard,where format of string depends on the control string"

EXAMPLE 1:

#include<Stdio.h>        // header file
printf("Printf function is used to print any data");         // prints the message hello world

Output:

Printf function is used to print any data

EXAMPLE 2

Printing Variables on Screen

#include<stdio.h>        //header  file
void main()
{
    int var1=10;
    float var2=20.26;
    char var3 = 'A';

    printf("integer variable var1 = %d\n",var1);        // %d format specifier used to print integer variable
    printf("Float variable var2 = %f\n",var2);        // %f format specifier used to print Float variable
    printf("Character variable var3 = %c\n",var3);     // %c format specifier used to print character variable
}

Output:

integer variable var1 = 10
Float variable var2 = 20.26
Character variable var3 = A

Scanf() Function

"This function is used to accept formatted data from the keyboard ,where format of string depends on the specifiers"

Syntax:

scanf("%d",&var);        // %d is specifier of integer variable which stores intger varaible

//examples 

scanf("%d",&var1);   // Accepts the decimal input from keyboard and stores to variable "var1"

scanf("%f",&var2);   // Accepts the floating number as  input from keyboard and stores to variable "var2"

scanf("%c",&var3);   // Accepts the character as input from keyboard and stores to variable "var3"

Note: Scanf() Functions Stores the Variable at certain Address.
Concept of Address we will see in "Pointer" Module,for now just remember this.

Example:

#include<stdio.h>              //header file


void main()
{
int  var1;
float var2;        //declarations of variables
char var3;

printf("\nEnter the value of integer variable:");
scanf("%d",&var1);                              //Input for integer variable.

printf("\nEnter the value of float variable:");
scanf("%f",&var2);                  //input for float variable.

printf("\nEnter the value of Character Variable:");
scanf("%c",&var3);           //input for character variable.

printf("Value of integer variable is %d\nValue of float variable is %f\nValue of character variable is %c",var1,var2,var3);
}

Output:

Enter the value of integer variable:10
Enter the value of float variable:14.2
Enter the value of Character Variable:J
Value of integer variable is 10
Value of float variable is 14.2
Value of character variable is J