fprintf and fscanf in C: solved exercise with text file

fprintf and fscanf in C: solved exercise with text file

This exercise is scheduled for daily publication and follows the same didactic structure used across the site: clear statement, compilable code, and expected output.

Problem statement

Implement a practical example of the topic and validate the output in the console.

C solution

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17

#include <stdio.h>

int main(void) {
    FILE *f = fopen("datos.txt", "w");
    if (!f) return 1;
    fprintf(f, "%s %d\n", "Ana", 28);
    fclose(f);

    char nombre[32];
    int edad;
    f = fopen("datos.txt", "r");
    if (!f) return 1;
    if (fscanf(f, "%31s %d", nombre, &edad) == 2)
        printf("%s tiene %d anos\n", nombre, edad);
    fclose(f);
    return 0;
}

Expected output

1

Ana tiene 28 anos

Common mistakes

  • Not validating input and standard-library return values.
  • Ignoring edge cases (buffers, limits, null pointers).
  • Skipping basic compile/run verification.

Practical use

fprintf and fscanf allow reading and writing formatted data to files, useful for logs, configurations, and reports.

Guided practice and full book

If you want a complete path with progressive difficulty:

FAQ

Is this exercise useful for C exams and technical interviews?

Yes. It targets patterns that commonly appear in practice assignments, technical interviews, and C programming exams.

Where can I keep practicing with more solved C exercises?

In Programming in C in 100 Solved Exercises and C Exercises. Kindle Unlimited: View on Amazon.

How should I practice this exercise type to improve faster?

Start with small inputs, run edge cases (empty, one item, max capacity), then rewrite the solution from scratch without copying.