The getc macro returns the next byte from the input stream
    specified by the file_ptr parameter and moves the file pointer,
    if defined, ahead one byte in the input stream.

    Since getc is a macro, a file pointer argument with side effects
    (for example, getc (*f++)) might be evaluated incorrectly.
    In such a case, use the fgetc function instead. See the fgetc
    function.

    See also getc_unlocked.