C Input and Output Functions

Last Updated on January 31, 2023 by Sumit Kumar

In this blog, we will learn about the input and output functions in the C programming language. To perform any code user must know how to give the input to the compiler and how to make the compiler show the output to us. The input and output functions are very necessary for programming and we will earn all about them all of the input and output functions like scanf c, printf c with their syntax and proper examples to use them.

Need of Input and Output Function in C

Before directly moving to the need for input and output let’s learn how generally the programming language works. In general, the programming language works in three steps. In the first step, the user gives the input to the compiler according to the requirements, In the second step the compiler works on the user-given input according to the instructions and in the final step the compiler gives the output. In c language, the most common input and output words you will use are scanf c and printf c.

What is Input in C?

Whenever you heard the word input what’s the first thing that comes to your mind that you have to provide the information to process? That’s the overall idea of input whereas in technical language Data entering into software is referred to as input. Data might come from a file or a command line. The C program maintains Random Access Memory as it runs. Data that is brought into a program from an outside source is known as input and is transferred to RAM so the program may access it. In c programming language there are various predefined functions that are used to take input from the user and feed it to the compiler like scanf c.

What is Output in C?

There is a very high chance that if you have heard the term input then you must have heard the term output. So whenever you have heard the term output the thing that comes to your mind is you are receiving something from the process or any machine. But in technical language the terms "output" and "just delivering data to the location out of program memory" refer to the same thing. The data’s final destination might be a screen, printer, or disc. It is not necessarily necessary to have input in order to acquire output; for example, a method for generating random numbers will simply produce random numbers in the absence of any input. In C programming language there are also various built-in functions for taking output like printf c.

Types of Output and Input Functions in C

In C programming language the input refers to feeding the information to the compiler and the output refers to displaying the information on the screen. The C language contains the library which contains input and output functions included in it we just have to mention the library and after that, we can use all the input and output functions.
The input and output functions are mainly divided into two types in C language and those are:

1. Formatted: In essence, the prepared functions receive or show the available data (input) in a predetermined format. There are several functions for input-output operations in the C standard library. These routines’ scanf c and printf c) methods assist programmers in formatting the functions in the way they like. These functions can be used by the software to read any type of data, including real numbers, integers, characters, and many more.

2. Unformatted: The format used to write and retrieve the available data cannot be controlled by the unformatted functions. As a result, these operations represent the most fundamental kinds of output and input. We refer to these functions as unformatted functions for input and output since neither the provision of input nor the presentation of output is permitted in user format.

The Format Specifiers in C language

In the c language, there are many format specifiers which are used while using input and output functions in the c language like scanf c and printf c.

1. printf() function

The printf c function is used to print the output of the given statements. To show any value, including float, integer, character, string, etc. on the console screen, a C program uses the printf c function. It is an already declared pre-defined function that is found in the stdio.h file (header file).

Syntax of printf c function
The printf c follows a general syntax and that is shown below:

printf("Format Specifier", var1, var2, ...., varn);  

Example of printing integer values
In the given example we will see the example to print the value of integer type variable in c using printf c.

Code implementation:

#include <stdio.h>
  
int main()
{
    int a;
  
    a = 22;
  
    printf("%d", a);
  
    return 0;
}

22

Explanation of the above code
In the above example we have seen an example to print the value of an integer using the printf c function. We have taken the value 22 in the example and hence printed the same value in the output as you can see in the above output image.

Example of printing string Values
In this example, we will learn how to output the value of a string in c using the printf c function with code and output.

Code Implementation:

#include <stdio.h>

// Driver code
int main()
{
    
    printf("This is an example to print string");
    return 0;
}

This is an example to print string

Explanation of the above code
As you can see in the above example that we have output the string using the printf c function. We have just written the content that we have to output in the double quotes inside the printf c function.

2. Scanf() Function

In a C application, the scanf c function is used to read or extract any value from the user’s keyboard. These values can be of any data type, including integer, float, character, string, and many more. This function is also a pre-defined function because it is declared in the header file stdio.h. We utilize the &(address-of operator) in the scanf() function to save the value of a variable on the variable’s memory location.

Syntax of scanf c function
The general syntax of the scanf c function is shown below you just have to follow this syntax to get or give the input to the compiler:

scanf("Format Specifier", &var1, &var2, ...., &varn);  

Example of taking integer as an input
In the following example we will see how to take an integer as in input from the user with the help of scanf c and then print it with the help of the compiler with the help of printf c.

Code implementation:

#include <stdio.h>
  
int main()
{
    int num1;
  
    
    printf("Enter a integer number: \n");
  

    scanf("%d", &num1);
  
    printf("You have entered %d", num1);
  
    return 0;
}

Enter a integer number: 
You have entered 10

Explanation of the above code
In the above code as you can see first we have asked the user to give the output by using the scanf c function and then whatever value the user has entered we will print that value using printf function and in the above example you can see we have entered the value 10. Hence, the compiler is printing the value 10 as output.

3. getchar() function

Many times you came across a situation when you have entered a lot of character but has to work only on one of them or the first one itself so in these type of cases the getchar function came into help as we can use scanf in c for normal input but If the user types numerous characters, the getchar() method is used to read only the first one. This function reads one character at a time until the enter key is pushed. In stdio.h, this function is declared (header file).

Syntax
Here we will see the general syntax of the getchar function whenever the user wants to work on the first character he can use the getchar function in c and whenever wants to work on the full input provided he can use scanf c.

Example of using getchar
In this example we will see the getchar function with proper example and code.

Code Implementation:

#include <stdio.h>

int main()
{
    char ch;

    printf("Enter the character: ");

    ch = getchar();

    printf("%c", ch);
    return 0;
}

Enter the character: a

Explanation of the above code
In the above code we have seen that when we entered a character getchar was able to read that single character like in the above example we entered the character n and hence the output is n.

4. putchar() function

Like getchar is used to read only a single variable the putchar is used to display a single variable only if we want to print the whole content we can use printf c. By supplying a character to the putchar() method directly or by passing a variable that has previously stored a character, one character can be shown at a time. In stdio.h, this function is declared (header file).

Syntax of putchar
The general syntax of putchar is explained in this section we just have to follow the general syntax to use the putchar in our code. This is the general syntax of putchar:

putchar(variable_name);  

Example of putchar
In this section, we will explain the example of putchar with proper code and explanation and will see how to use putchar in code as you know how to use scanf c and printf c in code.

Code Implementation:

#include <stdio.h>

int main()
{
    char ch;
    printf("Enter any character: ");

    // Reads a character
    ch = getchar();

    putchar(ch);
    return 0;
}

Enter any character: n

Explanation of the above example
In the above example we can see that we have only entered a single character using getchar and will print the single character using putchar.

5. gets()

The user enters a string or a collection of characters into the gets() method, which then stores the characters in a character array. We can enter space-separated texts or strings using this function. In stdio.h, this function is declared (header file).
Syntax of gets

char str[Length of string]; 
gets(str); 

Example of gets
In this section, we will explain the example of gets with proper code and explanation and will see how to use gets in code as you know how to use scanf c and printf c in code.

Code Implementation:

#include <stdio.h>

// Driver code
int main()
{
    
    char name[50];

    printf("Please enter some texts: ");

    gets(name);

    printf("You have entered: %s",
        name);
    return 0;
}

Please enter some texts: You have entered: n

Explanation of the above example
In the above example we have used printf c to show the output and gets to get the output instead of scanf c.

6. Puts() function

The puts() method in the C programming language is used to show a collection of characters or strings that have previously been saved in a character array. In stdio.h, this function is declared (header file).

Syntax of puts
Here we will show the general syntax of puts unction you just have to follow this syntax to use puts in the code.

puts(identifier_name );

Example of puts
In this section, we will discuss the example of the puts function with proper code and explanation of the same.

Code Implementation:

#include 


int main()
{
    char name[100];
    printf("Enter your text: \n");

    gets(name);

    printf("Your text is: ");


    puts(name);

    return 0;
}

Enter your text: 
Your text is: naman is a developer

Explanation of the above code
In the above code we have declared a character array name and have taken the input in that using gets and shown the output using puts instead of printf c and scanf c.

Conclusion
In the above blog we have studied various input and output operators present in c but before that, we have studied what is input and output in C language and about different types of operators, and studied one of the most used input and output operators in the language like scanf c and printf c followed by various higher level operators also.