/* Program to make a copy of an ASCII file.  Asks user for filenames. */

#include <stdio.h>
#include <stdlib.h>
FILE * open_user_file(char message[], char file_access_mode[]);

main() {
    FILE *f_in, *f_out;
    int ch;

    /* Call our own function to query user for filename & open file. */
    f_in = open_user_file("Copy which file?", "r");

    /* Ditto for output */
    f_out = open_user_file("Copy data to which file?", "w");

    /* Now copy characters one at a time until end of file on input. */
    ch = getc(f_in);
    while (ch != EOF) {
        putc(ch, f_out);
        ch = getc(f_in);
    }

    /* Now copied; close files. */
    fclose(f_in);
    fclose(f_out);
    printf("File has been copied\n");
    return 0;
}

/******* open_user_file *******
Prints the specified message, and reads a filename from the user.
Then opens that file in the specified file access mode.  If the
open fails, the function stops the program with an error message.
*/

FILE * file_open(char name[], char access_mode[]);

FILE * open_user_file(char message[], char file_access_mode[]) {
    char filename[81];
    FILE *f;

    printf("%s ", message);
    scanf("%80s%*c", filename);

    f = file_open(filename, file_access_mode);

    return f;
}

FILE * file_open (char name[], char access_mode[]) {
    FILE * f;
    f = fopen (name, access_mode);
    if (f == NULL) { /* error? */
        /* Library function perror prints an informative message. */
        perror ("Cannot open file");
        exit (1);  /* Terminate after printing error message. */
    }
    return f;      /* Only happens if fopen succeeded. */
}