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33 * @(#)strtol.c 8.1 (Berkeley) 6/4/93
40 * Convert a string to a long integer.
42 * Ignores `locale' stuff. Assumes that the upper and lower case
43 * alphabets and digits are each contiguous.
46 strtol(const char *nptr, char **endptr, int base)
52 int neg = 0, any, cutlim;
54 /* Be sensible about NULL strings */
60 * Skip white space and pick up leading +/- sign if any.
61 * If base is 0, allow 0x for hex and 0 for octal, else
62 * assume decimal; if base is already 16, allow 0x.
72 if ((base == 0 || base == 16) &&
73 c == '0' && (*s == 'x' || *s == 'X')) {
79 base = c == '0' ? 8 : 10;
82 * Compute the cutoff value between legal numbers and illegal
83 * numbers. That is the largest legal value, divided by the
84 * base. An input number that is greater than this value, if
85 * followed by a legal input character, is too big. One that
86 * is equal to this value may be valid or not; the limit
87 * between valid and invalid numbers is then based on the last
88 * digit. For instance, if the range for longs is
89 * [-2147483648..2147483647] and the input base is 10,
90 * cutoff will be set to 214748364 and cutlim to either
91 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
92 * a value > 214748364, or equal but the next digit is > 7 (or 8),
93 * the number is too big, and we will return a range error.
95 * Set any if any `digits' consumed; make it negative to indicate
98 cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
99 cutlim = cutoff % (unsigned long)base;
100 cutoff /= (unsigned long)base;
101 for (acc = 0, any = 0;; c = *s++) {
107 c -= isupper(c) ? 'A' - 10 : 'a' - 10;
112 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
121 acc = neg ? LONG_MIN : LONG_MAX;
126 *endptr = (char *)(any ? s - 1 : nptr);