[Logic_]

You can try experimenting with something like:

PHP Code:

// Open "file.txt" in "read only" mode
new File:handle = fopen("file.txt", io_read);
 
// If "file.txt" is open
if(handle) {
    // Jump to the last byte of "file.txt", and print its position
    printf("End of file position: %d", fseek(handle, 0, seek_end));
    fclose(handle);
} 


( Taken from SA-MP wiki https://sampwiki.blast.hk/wiki/Fseek )