STRTOL(3) BSD Library Functions Manual STRTOL(3)NAME
strtol, strtoll, strtoimax, strtoq — convert a string value to a long,
long long, intmax_t or quad_t integer
Standard C Library (libc, -lc)
strtol(const char * restrict nptr, char ** restrict endptr, int base);
strtoll(const char * restrict nptr, char ** restrict endptr, int base);
strtoimax(const char * restrict nptr, char ** restrict endptr, int base);
strtoq(const char *nptr, char **endptr, int base);
The strtol() function converts the string in nptr to a long value. The
strtoll() function converts the string in nptr to a long long value. The
strtoimax() function converts the string in nptr to an intmax_t value.
The strtoq() function converts the string in nptr to a quad_t value. The
conversion is done according to the given base, which must be between 2
and 36 inclusive, or be the special value 0.
The string may begin with an arbitrary amount of white space (as deter‐
mined 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
The remainder of the string is converted to a long, long long, intmax_t
or quad_t 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 35.)
If endptr is not NULL, strtol() stores the address of the first invalid
character in *endptr. If there were no digits at all, however, strtol()
stores the original value of nptr in *endptr. (Thus, if *nptr is not
‘\0’ but **endptr is ‘\0’ on return, the entire string was valid.)
The strtol(), strtoll(), strtoimax() and strtoq() functions return the
result of the conversion, unless the value would underflow or overflow.
If no conversion could be performed, 0 is returned and the global vari‐
able errno is set to EINVAL (the last feature is not portable across all
platforms). If an overflow or underflow occurs, errno is set to ERANGE
and the function return value is clamped according to the following ta‐
Function underflow overflow
strtol() LONG_MIN LONG_MAX
strtoll() LLONG_MIN LLONG_MAX
strtoimax() INTMAX_MIN INTMAX_MAX
strtoq() LLONG_MIN LLONG_MAX
[EINVAL] The value of base is not supported or no conversion
could be performed (the last feature is not portable
across all platforms).
[ERANGE] The given string was out of range; the value converted
has been clamped.
SEE ALSOatof(3), atoi(3), atol(3), strtod(3), strtonum(3), strtoul(3), wcstol(3)STANDARDS
The strtol() function conforms to ISO/IEC 9899:1990 (“ISO C90”). The
strtoll() and strtoimax() functions conform to ISO/IEC 9899:1999
(“ISO C99”). The BSD strtoq() function is deprecated.
BSD November 28, 2001 BSD