C putchar() Function | Print a Character to Standard Output

Introduction

The putchar() function in C is a standard library function that writes a single character to the standard output (stdout). It is part of the C standard library (stdio.h) and is commonly used for simple output operations.

Understanding putchar()

The putchar() function writes the character specified by the argument char to the standard output (stdout). It is useful for writing characters one at a time, handling output character by character, and for implementing features like character-based menus or simple text editors.

putchar() Function Syntax

The syntax for the putchar() function is as follows:

int putchar(int char);

Parameters:

• char: The character to be written to the standard output. It is passed as an int, but it is internally treated as an unsigned char.

Returns:

• The function returns the character written as an unsigned char cast to an int or EOF if an error occurs.

Examples

Writing a Single Character

To demonstrate how to use putchar() to write a single character to the standard output, we will write a simple program.

Example

#include <stdio.h>

int main() {
    int ch = 'A';

    // Write a single character to standard output
    putchar(ch);

    // Print a newline for clarity
    putchar('\n');

    return 0;
}

Output:

A

Using putchar() in a Loop

This example shows how to use putchar() in a loop to write multiple characters.

Example

#include <stdio.h>

int main() {
    char str[] = "Hello, World!";
    int i = 0;

    // Write each character of the string to standard output
    while (str[i] != '\0') {
        putchar(str[i]);
        i++;
    }

    // Print a newline for clarity
    putchar('\n');

    return 0;
}

Output:

Hello, World!

Real-World Use Case

Implementing a Simple Progress Indicator

In real-world applications, the putchar() function can be used to implement simple progress indicators that show progress one character at a time.

Example

#include <stdio.h>
#include <unistd.h> // For sleep function

int main() {
    int i;

    printf("Progress: ");

    for (i = 0; i < 10; i++) {
        // Simulate progress by printing a dot and flushing the output buffer
        putchar('.');
        fflush(stdout);

        // Sleep for 1 second to simulate work being done
        sleep(1);
    }

    // Print a newline for clarity
    putchar('\n');

    printf("Completed!\n");

    return 0;
}

Output:

Progress: ..........
Completed!

Conclusion

The putchar() function is a simple and efficient way to write a single character to the standard output. It is often used in programs where character-by-character output is required, such as in text processing or interactive console applications.