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.

Character I/O Functions
getchar() & putchar()

getchar() Function:

This function is used to Accept one character , from keyboard.
It takes Only One Character as an input.

syntax

character_var = getchar();

Example:

#include<stdio.h>            //header file

void main()
{
char a;
printf("Enter a character>");
a=getchar();         //getchar() funtion is  Assigned to variable a 
printf("You Entered  %c ",a);

}

Output:

Enter a character> A
You Entered A

The putchar() Function

This function is used to print one character on the screen, from keyboard.

syntax

character_var = getchar();  //accept character


putchar(character_var);   // display the accepted character

EXAMPLE

#include<stdio.h>

character_var = getchar();  //accept character  is 'A'

putchar(character_var);   // it will  display 'A' which is the accepted character

Output:

What if we give input more than one character,lets see whats happen when we give input as ABC

#include<stdio.h>

character_var = getchar();  //accept character 

putchar(character_var);   // it will  display 'A' which is the accepted character

Output:

Output is the same as above,Because getchar() Function neglect the other characters except of first character

Character I/O Functions
getch() & putch()

getch() Function:

This function is used to Accept one character , from keyboard ,without echo to the screen
Without echo means when we type non screen it is not visible.
This function provides functionality of not getting echo to the screen
This Function takes One Character as an input
Many programmer use this Function at the end of the program to stop screen until a Character is given as an input.(but its work is not to stop the screen,it Wait's for the character )

syntax

character_var = getch();

Example:

#include<stdio.h>


void main{
char var1;
printf("Enter The Character:");
var1 = getch();        //Not getting echo to the screen

printf("Character  was  %c",var1"); 

}

Output:

Enter the Character: A
Character was A

putch() Function:

This function is used to print one character ,on the screen
This Function also print One Character as an input

syntax

putch(variable_name);

Example:

#include<stdio.h>


void main{
char var1;
printf("Enter The Character>");
var1 = getchar();        //using getchar() function 

putch(var1); 

}

Ouput:

Enter the Charater>A
A

Character Input
getche()

getche() Function:

This function is used to Accept one character , from keyboard ,echo to the screen
This Function also takes One Character as an input

syntax

character_var = getche();

Example:

#include<stdio.h>


void main{
char var1;
printf("Enter The Character:");
var1 = getche();        // echo to the screen

printf("Character  was  %c",var1"); 

}