STRTOL(3) Linux Programmer's Manual STRTOL(3)
strtol, strtoll, strtoq - convert a string to a long integer.
strtol(const char *nptr, char **endptr, int base);
long long int
strtoll(const char *nptr, char **endptr, int base);
The strtol() function converts the initial part of 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 iss-
pace(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 (octal).
The remainder of the string is converted to a long int value in the obvious manner, stop-
ping 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 35.)
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 valid.
The strtoll() function works just like the strtol() function but returns a long long inte-
The strtol() function returns the result of the conversion, unless the value would under-
flow 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. Precisely the
same holds for strtoll() (with LLONG_MIN and LLONG_MAX instead of LONG_MIN and LONG_MAX).
ERANGE The resulting value was out of range.
EINVAL (not in C99) The given base contains an unsupported value.
The implementation may also set errno to EINVAL in case no conversion was performed (no
digits seen, and 0 returned).
In locales other than the "C" locale, also other strings may be accepted. (For example,
the thousands separator of the current locale may be supported.)
BSD also has
strtoq(const char *nptr, char **endptr, int base);
with completely analogous definition. Depending on the wordsize of the current architec-
ture, this may be equivalent to strtoll() or to strtol().
strtol() conforms to SVID 3, BSD 4.3, ISO 9899 (C99) and POSIX, and strtoll() to ISO 9899
(C99) and POSIX-2001.
atof(3), atoi(3), atol(3), strtod(3), strtoul(3)
GNU 2002-05-30 STRTOL(3)