Remove empty new line at the end of a file

Question

I have a file that's storing strings from the user's input (stdin)

However there are 2 situations

If I read it normally, my file will have an empty line at its end due to the newline from the last string the user introduced.

If I remove the \n from the input string, the file stores all strings in the same line, which is not wanted.

How can I simply remove that newline from the end of the file?

I can edit and provide some of my code if required.

EDIT: Let's say the last line of a file I already have is "cards"

when the cursor is in front of "cards", if I press the down arrow it doesn't go on to the next line, while in this case it can happen once.

For my code to function perfectly I can't let that happen,

Here's an example of what I have:

f=fopen(somefile, "w");
do
{
    fgets(hobby, 50, stdin);
    fprintf(f, "%s", hobby)

} while(strcmp(hobby,"\n") != 0);

Answer 1

The newline character¹ at the end of the file is part of the last line. Removing it is possible but makes the last line incomplete, which will break many programs. For example, concatenating another file at the end of this file will cause the last line to be merged with the first line of the concatenated file.

A Yuri Laguardia commented, if you later reopen this file in append mode to write more lines, the first one added would be concatenated at the end of this last incomplete line. Probably not the intended behavior.

If you do not want the file to contain empty lines, check user input before writing the line into the file:

void input_file_contents(FILE *fp) {
    char userinput[80];
    printf("enter file contents:\n");
    while (fgets(userinput, sizeof userinput, stdin)) {
        if (*userinput != '\n') {
            fputs(userinput, fp);
        }
    }
}

EDIT:

Your code does not test for termination at the right place: you write the empty line before the test. Do not use a do / while loop:

f = fopen(somefile, "w");
if (f != NULL) {
    /* read lines until end of file or empty line */
    while (fgets(hobby, 50, stdin) != NULL && *hobby != '\n') {
        fputs(hobby, f);
    }
}

---

¹ The newline character is actually a pair of bytes <CR><LF> on legacy systems.