Standard Input and Output in C Language

Introduction

Standard Input and Output (I/O) are fundamental concepts in C programming. They allow programs to interact with the user by receiving input and providing output. In C, the standard I/O library provides functions to perform these operations efficiently.

Standard Output

Standard output refers to the display screen where the output of a program is shown. The most commonly used function for standard output in C is printf().

#include <stdio.h>

int main() {
    printf("Hello, World!");
    return 0;
}
                

The printf() function can also be used to format strings with variables:

#include <stdio.h>

int main() {
    int age = 25;
    printf("I am %d years old.", age);
    return 0;
}
                

Standard Input

Standard input refers to the keyboard input. The most commonly used function for standard input in C is scanf().

#include <stdio.h>

int main() {
    int age;
    printf("Enter your age: ");
    scanf("%d", &age);
    printf("You are %d years old.", age);
    return 0;
}
                

The scanf() function reads formatted input from the standard input stream (keyboard).

Formatted I/O

Both printf() and scanf() use format specifiers to define the type of data being processed. Some common format specifiers include:

• %d - integer
• %f - floating point number
• %c - single character
• %s - string

Error Handling in I/O

While performing I/O operations, it is important to check for errors. The printf() and scanf() functions return values that can be used to detect errors.

#include <stdio.h>

int main() {
    int age;
    printf("Enter your age: ");
    if (scanf("%d", &age) != 1) {
        printf("Error reading input.");
        return 1;
    }
    printf("You are %d years old.", age);
    return 0;
}
                

Conclusion

Standard Input and Output are essential parts of C programming. Understanding how to use printf() and scanf() effectively will help you build interactive programs. Always remember to handle errors gracefully to ensure your programs are robust and user-friendly.