## table of contents

STRTOUL(3) | Linux Programmer's Manual | STRTOUL(3) |

# NAME¶

strtoul - convert a string to an unsigned long integer.# SYNOPSIS¶

#include <stdlib.h>unsigned long int strtoul(const char *nptr, char **endptr,intbase)

# 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.March 29, 1993 | GNU |