16进制字符串转16进制数字

int tolower(int c){if ((c >= 'A') && (c <= 'Z'))return c + ('a' - 'A');return c;}int htoi(char s[]){int i;int n = 0;if (s[0] == '0' && (s[1]=='x' || s[1]=='X')){i = 2;}else{i = 0;}for (; (s[i] >= '0' && s[i] <= '9') || (s[i] >= 'a' && s[i] <= 'f') || (s[i] >='A' && s[i] <= 'F');++i){if (tolower(s[i]) > '9'){n = 16 * n + (10 + tolower(s[i]) - 'a');}else{n = 16 * n + (tolower(s[i]) - '0');}}return n;}