What is the difference between printf, sprintf and fprintf?

The printf() function is used as a standard method for output operations and C also provides some different versions of this function such as sprintf() and fprintf(). These functions are also used for output operations but in different contexts.

The below table lists the primary differences between the printf, sprintf and fprintf in C:

Let's see each of them in detail one by one.

printf()

The printf function is used to print formatted output to the standard output, typically the console or terminal.

Example

#include <stdio.h>

int main() {
    int n = 42;

    // Print integer and floating-point
  	// number to the console
    printf("Number is %d", n);

    return 0;
}

Number is 42

Explanation: The above program demonstrates how to print to the console using the printf function in C by passing it inside a formatted string.

sprintf

The sprintf function is similar to printf, but instead of printing to the console, it stores the formatted string in a character array (string). This is useful when you need to generate a string dynamically for further processing.

Example

#include <stdio.h>

int main() {
    int n = 42;
    char res[50];

    // Store formatted output in a string
  	// using sprintf
    sprintf(res, "Number is %d.", n);

    // Print the string stored in result
    printf("%s", res);

    return 0;
}

Book is 42.

Explanation: The sprintf function is used to store the formatted string in the res array, which is then printed using printf.

fprintf

The fprintf function is used to print formatted output to a file or any other stream, such as a printer or a log file. It works similarly to printf, but the output is directed to a file specified by the FILE pointer.

Example

#include <stdio.h>

int main() {
    int n = 42;
    FILE *file = fopen("file.txt", "w");

    if (file != NULL) {
      
        // Write formatted output to a file
        fprintf(file, "Number is %d.\n", n);
        fclose(file);
        printf("Data written to output.txt\n");
    } else {
        printf("Error opening file.\n");
    }

    return 0;
}

Data written to output.txt

Explanation: The fprintf function is used to write the formatted string to the file output.txt. If the file is successfully opened, the formatted output is written, the file is closed, and the message "Data written to output.txt" is printed to the console.