STRTOL(3)

NAME
strtol, strtoll, strtoimax, strtoq - convert a string value to a long, long long, intmax_t or quad_t integer

LIBRARY
libc

SYNOPSIS
#include <stdlib.h>
#include <limits.h>
long
strtol(const char * restrict nptr, char ** restrict endptr, int base);
long long
strtoll(const char * restrict nptr, char ** restrict endptr, int base);
#include <inttypes.h>
intmax_t
strtoimax(const char * restrict nptr, char ** restrict endptr, int base);
#include <sys/types.h>
#include <stdlib.h>
#include <limits.h>
quad_t
strtoq(const char *nptr, char **endptr, int base);

DESCRIPTION
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 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 (octal).

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.)

RETURN VALUES
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 variable 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 table.
Function | underflow | overflow
strtol() | LONG_MIN | LONG_MAX
strtoll() | LLONG_MIN | LLONG_MAX
strtoimax() | INTMAX_MIN | INTMAX_MAX
strtoq() | LLONG_MIN | LLONG_MAX

ERRORS

[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 ALSO
atof(3), atoi(3), atol(3), strtod(3), strtonum(3), strtoul(3), wcstol(3)

STANDARDS
The strtol() function conforms to isoC. The strtoll() and strtoimax() functions conform to isoC-99. The BSD strtoq() function is deprecated.