.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
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.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified Sun Jul 25 10:54:03 1993 by Rik Faith (faith@cs.unc.edu)
.\" Fixed typo, aeb , 950823
.\"
.TH STRTOUL 3  "March 29, 1993" "GNU" "Linux Programmer's Manual"
.SH NAME
strtoul \- convert a string to an unsigned long integer.
.SH SYNOPSIS
.nf
.B #include <stdlib.h>
.sp
.BI "unsigned long int strtoul(const char *" nptr ", char **" endptr ,
.BR int " base" )
.fi
.SH DESCRIPTION
The \fBstrtoul()\fP function converts the string in \fInptr\fP to an
unsigned long integer value according to the given \fIbase\fP, which 
must be between 2 and 36 inclusive, or be the special value 0.
.PP
The string must begin with an arbitrary amount of white space (as
determined by
.BR isspace (3))
followed by a single optional `+' or `-'
sign.  If \fIbase\fP is zero or 16, the string may then include a 
`0x' prefix, and the number will be read in base 16; otherwise, a 
zero \fIbase\fP is taken as 10 (decimal) unless the next character
is `0', in which case it is taken as 8 (octal).
.PP
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.)
.PP
If \fIendptr\fP is not NULL, \fBstrtoul()\fP stores the address of the
first invalid character in \fI*endptr\fP.  If there were no digits at
all, \fBstrtoul()\fP stores the original value of \fInptr\fP in
\fI*endptr\fP.  (Thus, if \fI*nptr\fP is not `\\0' but \fI**endptr\fP
is `\\0' on return, the entire string is valid.)
.SH "RETURN VALUE"
The \fBstrtoul()\fP 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, \fBstrtoul()\fP returns ULONG_MAX and sets the global
variable \fIerrno\fP to ERANGE.
.SH "ERRORS"
.TP
.B ERANGE
The given string was out of range; the value converted has been clamped.
.SH "CONFORMING TO"
SVID 3, BSD 4.3, ISO 9899
.SH "SEE ALSO"
.BR atof "(3), " atoi "(3), " atol "(3), " strtod "(3), " strtol (3)
.SH BUGS
Ignores the current locale.