程序员面试100题(算法)之把字符串转换成整数

此程序还没有判读sum是否溢出，待续。。

// 程序员面试100题(算法)之把字符串转换成整数#include "stdafx.h"#include <iostream>using namespace std;int state = 0;int ConvertStr(char *str){int num = 0;long sum = 0;if(NULL == str){cout << "input is empty" << endl;state = 1;}else{char symbol = *str;if(symbol == '+' || symbol == '-'){str++;}while(*str != '\0'){if(*str >= '0' && *str <= '9'){num = *str - '0';sum = sum * 10 + num;str++;}else{state = 1;break;}}if(symbol == '-'){sum = 0 - sum;}}return sum;}int _tmain(int argc, _TCHAR* argv[]){char *str = "-5462458";long number = ConvertStr(str);if(1 == state)cout << "Wrong input" <<endl;elsecout << number << endl;return 0;}