strtol - convert a string to a long integer.
nptr, char **endptr, int base);
The strtol() function converts the string in
nptr to a long integer value according to the given
base, which must be between 2 and 36 inclusive, or be
the special value 0.
The string must begin with an arbitrary amount of white
space (as determined by isspace(3)) followed by a
single optional `+' or `-' sign. If base is zero or
16, the string may then include a `0x' prefix, and the
number will be read in base 16; otherwise, a zero
base is taken as 10 (decimal) unless the next
character is `0', in which case it is taken as 8
The remainder of the string is converted to a long int value
in the obvious manner, stopping at the first character which
is not a valid digit in the given base. (In bases above 10,
the letter `A' in either upper or lower case represents 10,
`B' represents 11, and so forth, with `Z' representing
If endptr is not NULL, strtol() stores the
address of the first invalid character in *endptr. If
there were no digits at all, strtol() stores the
original value of nptr in *endptr (and returns
0). In particular, if *nptr is not `0' but
**endptr is `0' on return, the entire string is
The strtol() function returns the result of the
conversion, unless the value would underflow or overflow. If
an underflow occurs, strtol() returns LONG_MIN. If an
overflow occurs, strtol() returns LONG_MAX. In both
cases, errno is set to ERANGE.
The given string was out of range; the value converted has
SVID 3, BSD 4.3, ISO 9899
atof(3), atoi(3), atol(3),
Ignores the current locale.