http://blog.csdn.net/zwb8848happy/article/details/7340634

输入一个表示整数的字符串，把该字符串转换成整数并输出

//Analysis: 
//1. Whether it is a negative number 
//2. Whether there exist other characters that do not represent numbers
//#include <iostream>
#include <string>
#include <assert.h>
#include <stdio.h>
#include <ctype.h>


using namespace std;


char num[100], len_Num;


void Convert(char *str)
{
int len_str, i, isPosiNum = 1, result;
char check[100];


len_str = strlen(str) - 1;
assert(len_str > 0);
len_Num = 0;
isPosiNum = str[0] == '-' ? 0 : 1;
for (i = 0; i < len_str; i++)
{
if (isdigit(str[i]))
{
num[len_Num++] = str[i];
}
}
sscanf_s(num,"%d",&result);
sprintf_s(check,"%d",result);
if (strcmp(check, num) != 0)
{
printf("溢出\n");
return;
}


if (isPosiNum == 0)
{
printf("The result is:-%d\n\n", result);
}
else
{
printf("The result is: %d\n\n", result);
}
}


int main()
{
char str[100];
while (printf("Please input a string :  "), fgets(str, sizeof(str), stdin) != NULL)
{
Convert(str);
}
return 0;
}