Editing C file input/output (section)

==Example==
The following C program opens a binary file called ''myfile'', reads five bytes from it, and then closes the file.

<syntaxhighlight lang="c">
#include <stdio.h>
#include <stdlib.h>

int main(void) {
    char buffer[5];
    FILE* fp = fopen("myfile", "rb");

    if (fp == NULL) {
        perror("Failed to open file \"myfile\"");
        return EXIT_FAILURE;
    }

    if (fread(buffer, 1, 5, fp) < 5) {
        fclose(fp);
        fputs("An error occurred while reading the file.\n", stderr);
        return EXIT_FAILURE;
    }

    fclose(fp);

    printf("The bytes read were: ");
    for (int i = 0; i < 5; ++i) {
        printf("%02X ", buffer[i]);
    }
    putchar('\n');

    return EXIT_SUCCESS;
}
</syntaxhighlight>