source: downloads/tcl8.5.2/compat/strtol.c @ 42

/* 
 * strtol.c --
 *
 *      Source code for the "strtol" library procedure.
 *
 * Copyright (c) 1988 The Regents of the University of California.
 * Copyright (c) 1994 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution of
 * this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: strtol.c,v 1.6 2007/04/16 13:36:34 dkf Exp $
 */

#include <ctype.h>
#include "tclInt.h"

/*
 *----------------------------------------------------------------------
 *
 * strtol --
 *
 *      Convert an ASCII string into an integer.
 *
 * Results:
 *      The return value is the integer equivalent of string. If endPtr is
 *      non-NULL, then *endPtr is filled in with the character after the last
 *      one that was part of the integer. If string doesn't contain a valid
 *      integer value, then zero is returned and *endPtr is set to string.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

long int
strtol(
    CONST char *string,         /* String of ASCII digits, possibly preceded
                                 * by white space. For bases greater than 10,
                                 * either lower- or upper-case digits may be
                                 * used. */
    char **endPtr,              /* Where to store address of terminating
                                 * character, or NULL. */
    int base)                   /* Base for conversion. Must be less than 37.
                                 * If 0, then the base is chosen from the
                                 * leading characters of string: "0x" means
                                 * hex, "0" means octal, anything else means
                                 * decimal. */
{
    register CONST char *p;
    long result;

    /*
     * Skip any leading blanks.
     */

    p = string;
    while (isspace(UCHAR(*p))) {
        p += 1;
    }

    /*
     * Check for a sign.
     */

    if (*p == '-') {
        p += 1;
        result = -(strtoul(p, endPtr, base));
    } else {
        if (*p == '+') {
            p += 1;
        }
        result = strtoul(p, endPtr, base);
    }
    if ((result == 0) && (endPtr != 0) && (*endPtr == p)) {
        *endPtr = (char *) string;
    }
    return result;
}