[leetcode]-7. Reverse Integer（C语言）

Given a 32-bit signed integer, reverse digits of an integer.
Example 1:Input: 123
Output: 321
Example 2:Input: -123
Output: -321
Example 3:Input: 120
Output: 21
Note:
Assume we are dealing with an environment which could only hold integers within the 32-bit signed integer range. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.
主要注意的是溢出问题：如果溢出，则系统只取低32位，会造成结果错误。
int reverse(int x) {
int result,sum=0;
int b;
while(x)
{
b=x%10;
result=sum*10+b;
x=x/10;
if((result-b)/10!=sum) //判断是否溢出
return 0;
sum=result;

}
if(sum>2147483648)
return 0;
return sum;
}