How to use feof and ferror for fgets (minishell in C) [duplicate]

Answer 1

fgets(str, LINE_LEN, stdin);

if (str==NULL) {
    goto errorfgets;
}

That's not how you check the return value of fgets. What's more, in your code str will never be NULL by definition. You want something like:

if (!fgets(....)) }
    /* error handling. */
}

Answer 2

First of all, your test:

fgets(str, LINE_LEN, stdin);

[...]

if (str==NULL) {
    goto errorfgets;
}

is wrong. The str parameter is passed by value and cannot be modified by fgets(). Instead, you should be checking the value returned by fgets() (returns NULL on EOF or error).

Regarding your specific question: fgets() does not "return" feof or ferror. Both feof() and ferror() are actually functions (see the man pages). You would use this as follows:

if (!fgets(str, LINE_LEN, stdin)) {
    /* fgets returns NULL on EOF and error; let's see what happened */
    if (ferror(stdin)) {
        /* handle error */
    } else {
        /* handle EOF */
    }
}

Answer 3

You can use feof like this.

#open a file
fd = fopen (testFile,"r+b");

#read some data from file 
fread (&buff, 1, 1, fd);
..
..
..
#To check if you are at the end of file
if (feof (fd))
{
    printf("This is end of file");
}else{
    printf("File doesn't end. Do continue...");
}