Write Output

A program can format a result into a file and then read that result back for verification.

write_output.c

#include <stdio.h>

int main(void) {
    int width = ;
    int height = 5;
    int area = width * height;
    FILE *file = fopen("write_output_demo.txt", "w+");

    if (file == 0) {
        return 1;
    }

    fprintf(file, "area=%d\n", area);
    rewind(file);

    char label[8];
    int read = 0;
    fscanf(file, "%7[^=]=%d", label, &read);

    fclose(file);
    remove("write_output_demo.txt");

    printf("area=%d\n", read);
    return 0;
}

#include <stdio.h>

int main(void) {
    int width = ;
    int height = 5;
    int area = width * height;
    FILE *file = fopen("write_output_demo.txt", "w+");

    if (file == 0) {
        return 1;
    }

    fprintf(file, "area=%d\n", area);
    rewind(file);

    char label[8];
    int read = 0;
    fscanf(file, "%7[^=]=%d", label, &read);

    fclose(file);
    remove("write_output_demo.txt");

    printf("area=%d\n", read);
    return 0;
}

#include <stdio.h>

int main(void) {
    int width = ;
    int height = 5;
    int area = width * height;
    FILE *file = fopen("write_output_demo.txt", "w+");

    if (file == 0) {
        return 1;
    }

    fprintf(file, "area=%d\n", area);
    rewind(file);

    char label[8];
    int read = 0;
    fscanf(file, "%7[^=]=%d", label, &read);

    fclose(file);
    remove("write_output_demo.txt");

    printf("area=%d\n", read);
    return 0;
}

formatted output `fprintf` writes formatted text to the file stream.

read back Reading the output back confirms the formatted result.