The atoq (or atoll) function converts the initial portion of
    a string to its decimal __int64 value. This function does not
    account for overflows resulting from the conversion. The string
    to be converted has the following format:

    [white-spaces][+|-]digits

    The function call atoq (str) is equivalent to strtoq (str,
    (char**)NULL, 10), except for the behavior on error.