What is Include Stdio in C/C++?

Why we use #include?

In C and C++ programming languages, #include is a preprocessor directive that is used to include the contents of a header file into the source file. This allows you to access the declarations, macros, constants, and other functionalities defined in the header file within your source code.

For example, #include <stdio.h> is commonly used to include the standard input-output library in C and C++ programs. This header file contains declarations for standard input and output functions like printf(), scanf(), fprintf(), fscanf(), putc(), getc(), etc.

Important Points in Stdio.h

Here are some important points about stdio.h:

1. Standard I/O Functions: stdio.h provides declarations for standard input and output functions that are used to read data from the keyboard (scanf(), getchar()) and write data to the screen or files (printf(), putchar()).
    
2. File Operations: It also provides functions to perform file input and output operations (fopen(), fclose(), fread(), fwrite(), fprintf(), fscanf(), etc.).
    
3. Constants: stdio.h defines constants such as EOF (End Of File) which is returned by input functions when the end of file is reached.
    
4. File Pointers: It declares the FILE data type and related functions for file handling. File pointers such as FILE * are used to access files in C programs.
    
5. Buffering: stdio.h provides functions for buffering I/O operations, which helps in improving the efficiency of input and output operations.
    
6. Error Handling: It includes functions for error handling and reporting such as perror() and feof().

Stdio.h Library Variables:

Stdio.h provides a few important variables that can be used for input and output operations:

Stdio.h Library Functions:

Some of the Stdio.h Library used functions are:

These functions enable programs to communicate effectively with users, display information, read input, and manage files.

Importance of Include Stdio in C/C++?

We often see #include <stdio.h> at the beginning of any C/C++ programs. This phrase plays an important role in the efficient functioning of our code. They are like instruction manuals that direct the basic construction of the code. It is abbreviated as standard input and output.

This means that by including this library, we are authorizing the C/C++ code to accept direct inputs from the user by various methods.

In other words, the header file defines the input and output domains of the code. In its absence, the computer will fail to identify the basic building blocks of the program.

Purpose of the #include Directive in C/C++

• In C/C++ programming, we use a "header file" to help us perform specific tasks, such as taking inputs or using standard templates.
   
• The #include directive is a special command to tell the computer to include these header files in our program. When the program control encounters it, it successfully identifies the instructions of that particular library for the rest of the code.
   
• Using the #include directive saves time and effort because we don't have to write all these instructions ourselves. In order words, we avoid creating containers from scratch by including them in the code.
   
• Different header files contain different instructions, so we use different #include commands to include different header files. For example, we use #include<math.h> to include the header file that contains instructions for mathematical operations.

Role of the stdio.h Header File in C/C++

The roles of the stdio.h Header File in C/C++ goes as follows:
 

• In C/C++ programming, the stdio.h header file is a necessary file that aids the program control in identifying the input and output instructions.
   
• When we want to print something to the screen, like a message or a number, we use a function called "printf". Since it is included in the stdio.h directory, we don’t need to implement “printf” from the beginning.
   
• Similarly, when we want to read some input from the user, like their name or age, we use a function called "scanf". This function is also included in the stdio.h header file.
   
• In conclusion, we can imagine stdio.h as a universal help center that provides users with the basic tools to implement containers smoothly. It also helps to shrink the code length.
   
• Without the stdio.h header file, we couldn't use functions like printf and scanf in our program, which will exponentially increase our efforts to implement them.

Utilities of the stdio.h Header File

The stdio.h header file contains many important functions, such as:
 

• printf: This function is responsible for printing the results of the concerned code in C on the screen. Hence, it is necessary for interactive problems or when a user expects some output. The cout function also plays the same role.
   
• scanf: This function is used to read input from the user. We can get input like names, ages, and other values. The cin function also plays the same role.
   
• getchar: This function reads only a single character of input from the user. We can use it to get input of any data type with a maiden length.
   
• putchar: This function displays a single character on the screen or console. We can use it to show letters, numbers, and other characters. 
   
• gets: This function reads a whole line of text input from the user. We can use it to get input like sentences. It helps to encounter cases where we need to input multiple space characters. 
   
• puts: This function displays a whole line of text on the screen or console. We can use it to show things like sentences or paragraphs.

Examples

Before diving into some of the examples of how to use the functions defined in stdio.h for input/output operations in C/C++ programs, we will first see what happens if we do not include the header file in our program and the error it throws;

The program below is a basic program to print “Hello!” but we did not include the include stdio header file.

int main()
{
     cout << “Hello” ;
     return 0 ;
} 

On compilation, the above code throws the following error:

Examples of correct implementation of the header file are as follows:

• C++

C++

#include <stdio.h>
int main() 
{
   char name[30];
   int age;
   printf("Enter your name:");
   scanf("%s", name);
   printf("\n");
   printf("Your name is: %s\n",name);
   printf("Enter your age: ");
   scanf("%d", &age);
   printf("Your age is: %d\n", age);
   return 0;
}

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Output:
 

• C++

C++

#include <stdio.h>
int main() 
{
  	char ch;
  	printf("Enter any character"); 
  	printf ("\n");
  	ch = getchar();
  	printf("The character is : %c", ch );
  	return 0;
}

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Output:

• C++

C++

#include <stdio.h>
int main() 
{
  	char lines[100];
  	printf("Enter a sentence: ");
  	gets(lines);
   	printf("\n");
  	printf("Your sentence was: ");
  	puts(lines);
  	return 0;
}

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Output:

Implementing the concerned header file is extremely important for even a beginner-level code to run properly.

Guidelines for including Header Files in C/C++

• Prefer to include the header files at the beginning of the code.
   
• Only include those header files that are necessary.
   
• Avoid name conflicts when using header files.
   
• For convenience in competitive programming, the user may write #include <bits/stdc++.h>.
   
• Include all necessary header files to identify all necessary containers, which we will use in the code.
   
• Properly check the header file's syntax, uppercase and lowercase characters.

Frequently Asked Questions

What is the use of #include stdio H in C++?

Using #include <stdio.h> in C++ allows access to the functionalities of the C Standard I/O library. This provides functions for input/output operations, helping to display the output and receive input from the user.

What is the stdio h header file in C?

In C, stdio.h header file is a component of the C Standard Library. It provides functions and macros for input and output operations, such as displaying output on the screen and reading input from the user or files.

What is #include in C?

In C, #include a preprocessor directive to import external files, such as header files, into your program. It allows to access the functionalities present in the included file and improves the program's capabilities.

Conclusion

In Summary, the #include directive brings in external code from header files like stdio.h to use functions and variables in our programs. Understanding how to use them is crucial for efficient and organized C/C++ programming. Following best practices and avoiding errors ensures correct program functionality.

To learn more about C and C++ programming, visit the below links

• #include in C
• Getch in C

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