Why is my file pointer always NULL, even with text in it?

Question

I am having trouble opening and parsing a file in C. As of now I am trying to open a file and print out the current line then the next until the program reaches the end of the file. However, the file pointer always returns NULL and does not read the file.

This is my function:

int file_parse() {
    char filename[100];
    printf("Enter the filename: ");
    scanf("%s", filename); //Get filename
    printf("\nYou want to encrypt or decrypt with file: %s", filename); //Confirm filename

    int origin[27];
    int final[27];

    FILE *fp;

    if ((fp = fopen(filename, "r")) != NULL) {
        char current_line[250];

        while (!feof(fp)) {
            fgets(current_line, 250, fp);
            printf("The current line is: %s", current_line);
        }

        fclose(fp);

    } else {
        printf("\nError! Cannot open the specified file.");
        exit(EXIT_FAILURE);
    }
}

Relevant: https://stackoverflow.com/questions/5431941/why-is-while-feof-file-always-wrong — Carl Norum, Sep 17 '19 at 21:51
Try using an absolute pathname, the program may not be running in the directory you expect. — Barmar, Sep 17 '19 at 21:54
There's nothing wrong with the way you're opening the file, so the problem has to be with the filename. — Barmar, Sep 17 '19 at 21:55
The program was being executed in a different directory; @Barmar was correct in their assumption. — , Sep 17 '19 at 22:00
If only the `fopen` function provided some way to get an explanation when it failed. Oh well, we can dream. — David Schwartz, Sep 17 '19 at 23:50
Nate, good that code had `if ((fp = fopen(filename, "r")) != NULL)`, error checking is so worth it. — chux - Reinstate Monica, Sep 18 '19 at 00:18
Aside: change `while (!feof(fp)) { fgets(current_line, 250, fp);` to `while (fgets(current_line, sizeof current_line fp) {`. — chux - Reinstate Monica, Sep 18 '19 at 00:19
`feof(fp)` **only** tells you if you are at eof **after** a call to a reading stdio routine, so calling it first will make your program fail. Just do what @chux suggests. — Luis Colorado, Sep 20 '19 at 07:51

Why is my file pointer always NULL, even with text in it?

0 Answers0