8、String to Integer (atoi)
轉換字符串到整數
"10" =>10
"-1" => -1
"123123123123123" => 2147483647
"1.0" => 1
代碼:
class Solution {
public:
int myAtoi(string str) {
int FF=1;//判斷首位是否是+,-號
long result=0;
str.erase(0, str.find_first_not_of(' '));//除去字符串首空格
int i=0;
if(str[0]=='-')FF=-1,i=1;
else if(str[0]=='+')FF=1,i=1;
for(i;i<str.length();i++)
{
if(str[i]<='9'&&str[i]>='0')
result=result*10+(str[i]-'0');
else return result*FF;
if(result*FF >= INT_MAX) return INT_MAX;//判斷是否溢出
if(result*FF <= INT_MIN) return INT_MIN;
}
return result*FF;
}
};