NAME¶

strtoul - convert a string to an unsigned long integer.

SYNOPSIS¶

#include <stdlib.h>

unsigned long int strtoul(const char *nptr, char **endptr,
int base)

DESCRIPTION¶

The strtoul() function converts the string in nptr to an unsigned 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 (octal).

The remainder of the string is converted to an unsigned 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 35.)

If endptr is not NULL, strtoul() stores the address of the first invalid character in *endptr. If there were no digits at all, strtoul() stores the original value of nptr in *endptr. (Thus, if *nptr is not `\0' but **endptr is `\0' on return, the entire string is valid.)

RETURN VALUE¶

The strtoul() function returns either the result of the conversion or, if there was a leading minus sign, the negation of the result of the conversion, unless the original (non-negated) value would overflow; in the latter case, strtoul() returns ULONG_MAX and sets the global variable errno to ERANGE.

ERRORS¶

ERANGE

The given string was out of range; the value converted has been clamped.

CONFORMING TO¶

SVID 3, BSD 4.3, ISO 9899

SEE ALSO¶

atof(3), atoi(3), atol(3), strtod(3), strtol(3)

BUGS¶

Ignores the current locale.