Text file format convert

dos2unix.c

#include <stdio.h>
#include <stdlib.h>
int main(int argc, char* argv[]) {

    FILE *fp;
    if (argc != 2 ||
       (fp = fopen(argv[1], "r")) == NULL) {

        perror("File opening failed");
        return EXIT_FAILURE;
    }
    int c;
    while((c = fgetc(fp)) != EOF) {
        if(c == '\r') {
            /* skip */
        } else {
            putchar(c);
        }
    }
    if (ferror(fp)) {
        fprintf(stderr, "I/O error when reading\n");
    }
    else if (feof(fp)) {
        /* End of file reached successfully */
    }
    fclose(fp);
    return 0;
}

unix2dos.c

#include <stdio.h>
#include <stdlib.h>
int main(int argc, char* argv[]) {

    FILE *fp;
    if (argc != 2 ||
       (fp = fopen(argv[1], "r")) == NULL) {

        perror("File opening failed");
        return EXIT_FAILURE;
    }
    int c;
    while((c = fgetc(fp)) != EOF) {
        if(c == '\n') {
            printf("\r\n");
        } else {
            putchar(c);
        }
    }
    if (ferror(fp)) {
        fprintf(stderr, "I/O error when reading\n");
    }
    else if (feof(fp)) {
        /* End of file reached successfully */
    }
    fclose(fp);
    return 0;
}