Formatted Input and Output in C with Example

Input and Output in C – Input refers to the act of providing data to software.

A file or the command line can be used to provide an input.

The built-in functions in C programming make it possible to read the input and pass it along to the program as needed.

The term “output” refers to the presentation of data in a file, on the screen, or on a printer.

A collection of built-in functions for C programming are available to output data to the computer screen as well as save it to text or binary files.

Standard Files

Every device is treated as a file in C programming.

In order to allow access to the keyboard and screen while a program runs, the following three files are automatically opened.

Devices like the display are thus accessed in the same way as files.

Standard FileFile PointerDevice
Standard inputstdinKeyboard
Standard outputstdoutScreen
Standard errorstderrYour screen

Example 1 of Output in C

#include <stdio.h>    
int main()
{ 
    // Displays the string inside quotations
    printf("C Programming Tutorial in Input and Output");
    return 0;
}

Output of the above example:

C Programming Tutorial in Input and Output

How does this program work?

  • The main() function must be present in every legitimate C program. The main() function is where the code execution starts.

  • A library function called printf() is used to display formatted output on screens. The string is printed within quote marks by the function.

  • We must use the #include stdio.h> declaration to include the stdio.h header file in order to use printf() in our application.

  • The main() function’s return 0; line represents the program’s “Exit status.” It’s not required.

You can test the above example here! ➡ C Online Compiler

Example 2 of Integer Output in C

#include <stdio.h>
int main()
{
    int exampleInteger = 45;
    printf("Number = %d", exampleInteger);
    return 0;
}

Output of the above example:

Number = 45

To print int types, we utilize the percent d format specifier.

Here, the value of exampleInteger will be used in place of the percentage d enclosed in quote marks.

You can test the above example here! ➡ C Online Compiler

Example 3 of float and double Output in C

#include <stdio.h>
int main()
{
    float testnum1 = 45.5;
    double testnum2 = 35.4;
    printf("number1 = %f\n", testnum1);
    printf("number2 = %lf", testnum2);
    return 0;
}

Output of the above example:e

number1 = 45.500000
number2 = 35.400000

We utilize the percent %f format specifier to output float. In the same manner, we print double numbers by using percent %lf.

You can test the above example here! ➡ C Online Compiler

Example 4 of Print Characters in C Output

#include <stdio.h>
int main()
{
    char chr = 'x';    
    printf("character = %c", chr);  
    return 0;
} 

Output of the above example:

character = x

We employ the percent %C format specifier to print char.

You can test the above example here! ➡ C Online Compiler

Input in C

One of the often used functions in C programming to receive user input is scanf().

Using common input devices like keyboards, the scanf() function reads formatted input.

Example 5 of Integer Input and Output in C

#include <stdio.h>
int main()
{
    int exampleInteger;
    printf("Enter an integer: ");
    scanf("%d", &exampleInteger);  
    printf("Number = %d",exampleInteger);
    return 0;
}

Output of the above example:

Enter an integer:30
Number = 30

In order to accept int input from the user, we have utilized the percent d format specifier inside the scanf() function.

An integer is entered by the user and kept in the testInteger variable.

You can test the above example here! ➡ C Online Compiler

Example 6 of Float and Double Input and Output in C

#include <stdio.h>
int main()
{
    float number1;
    double number2;
    printf("Enter a number: ");
    scanf("%f", &number1);
    printf("Enter another number: ");
    scanf("%lf", &number2);
    printf("number1= %f\n", number1);
    printf("number2= %lf", number2);
    return 0;
}

Output of the above example:

Enter a number:45
Enter another number:69
number1= 45.000000
number2= 69.000000

For float and double, we utilize the percent %f and percent %lf format specifiers, respectively.

You can test the above example here! ➡ C Online Compiler

Example 7 of Character Input and Output in C

#include <stdio.h>
int main()
{
    char character;
    printf("Enter a character: ");
    scanf("%c",&character);     
    printf("You entered %c.", character);  
    return 0;
}   

Output of the above example:

Enter a character: x
You entered x.

The character itself is not kept when a character is typed into the application mentioned above by the user.

An integer value (ASCII value) is instead kept on file.

You can test the above example here! ➡ C Online Compiler

Input and Output Multiple Values in C Program

Here’s how to display multiple user inputs after accepting numerous inputs.

Most of the time, novice programmers are looking for methods to have a function return more than one value.

Unfortunately, C directly prohibits this.

Example 9 of Input and Output Multiple Values in C

#include <stdio.h>
int main()
{
    int x;
    float y;
    printf("Enter integer and then a float: ");
  
    // Taking multiple inputs
    scanf("%d%f", &x, &y);
    printf("You entered %d and %f", x, y);  
    return 0;
}

Output of the above example:

Enter integer and then a float: 45
5.9
You entered 45 and 5.900000

You can test the above example here! ➡ C Online Compiler

Format Specifiers for Input and Output in C

From the above examples, you can see that we use

  • %d for int
  • %f for float
  • %lf for double
  • %c for char

This section lists the most popular C data types and the format specifiers used with them.

Data TypeFormat Specifier
int%d
char%c
float%f
double%lf
short int%hd
unsigned int%u
long int%li
long long int%lli
unsigned long int%lu
unsigned long long int%llu
signed char%c
unsigned char%c
long double%Lf

Summary

In this course, we learned about the C language’s input and output.

We learned how to utilize the printf() and scanf() functions in code to display output to and collect input from users, respectively.

A few other functions for displaying results and accepting user input were also covered.

If you have any questions or suggestions about What is Formatted Input and Output Function in C Language, please feel free to leave a comment below.

About Next Tutorial

In the next following post, I’ll create a File Input and Output in C and try to explain its many components in full detail.

I hope you enjoy this post on What is Formatted Input and Output Function in C Language, in which I attempt to illustrate the language’s core grammar.


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