字符串转换成整数

int StrToInt(const char * str){static const int MAX_INT = (int) ((unsigned) ~ 0 >> 1);static const int MIN_INT = - (int) ((unsigned) ~ 0 >> 1) - 1;unsigned int n = 0; // 判断输入是否为空 if (str == 0) { return 0; } // 处理空格 while (isspace(*str)) { ++str; } // 处理正负 int sign = 1; if (*str == '+' || *str == '-') { if (*str == '-') { sign = -1; } ++str; } // 确定是数字后才执行循环 while (isdigit(*str)) { // 处理溢出 int c = *str - '0'; if (sign > 0 && (n > MAX_INT / 10 || (n == MAX_INT / 10 && c > MAX_INT % 10))) { n = MAX_INT; break; } else if (sign < 0 && (n > (unsigned) MIN_INT / 10 || (n == (unsgined) MIN_INT / 10 && c > (unsigned) MIN_INT % 10))) { n = MIN_INT; break; } // 把之前得到的数字乘以10，再加上当前字符表示的数字 n = n * 10 + c; ++str; } return sign > 0 ? n : -n;}