c - fopen() returning a NULL pointer, but the file definitely exists

Question

The code I have is as follows:

FILE *txt_file = fopen("data.txt", "r");
if (txt_file == NULL) {
    perror("Can't open file");
} 

The error message returned is:

Can't open file: No such file or directory

The file 'data.txt' definitely exists in the working directory (it exists in the directory that contains my .c and .h files), so why is fopen() is returning a NULL pointer?

Answer 1

Standard problem. Try

FILE *txt_file = fopen("C:\SomeFolder\data.txt", "r");

I.e. try opening it with the full absolute path first ; if it works then you just have to figure out what the current directory is with _getcwd() and then fix your relative path.