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29 * @(#)strtol.c 8.1 (Berkeley) 6/4/93
36 * Convert a string to a long integer.
38 * Ignores `locale' stuff. Assumes that the upper and lower case
39 * alphabets and digits are each contiguous.
42 strtol(const char *nptr, char **endptr, int base)
48 int neg = 0, any, cutlim;
50 /* Be sensible about NULL strings */
56 * Skip white space and pick up leading +/- sign if any.
57 * If base is 0, allow 0x for hex and 0 for octal, else
58 * assume decimal; if base is already 16, allow 0x.
68 if ((base == 0 || base == 16) &&
69 c == '0' && (*s == 'x' || *s == 'X')) {
75 base = c == '0' ? 8 : 10;
78 * Compute the cutoff value between legal numbers and illegal
79 * numbers. That is the largest legal value, divided by the
80 * base. An input number that is greater than this value, if
81 * followed by a legal input character, is too big. One that
82 * is equal to this value may be valid or not; the limit
83 * between valid and invalid numbers is then based on the last
84 * digit. For instance, if the range for longs is
85 * [-2147483648..2147483647] and the input base is 10,
86 * cutoff will be set to 214748364 and cutlim to either
87 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
88 * a value > 214748364, or equal but the next digit is > 7 (or 8),
89 * the number is too big, and we will return a range error.
91 * Set any if any `digits' consumed; make it negative to indicate
94 cutoff = neg ? -(unsigned long)LONG_MIN : LONG_MAX;
95 cutlim = cutoff % (unsigned long)base;
96 cutoff /= (unsigned long)base;
97 for (acc = 0, any = 0;; c = *s++) {
103 c -= isupper(c) ? 'A' - 10 : 'a' - 10;
108 if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
117 acc = neg ? LONG_MIN : LONG_MAX;
122 *endptr = (char *)(any ? s - 1 : nptr);