8. String to Integer (atoi)

public class Solution {
public int myAtoi(String str) {
if(str.length()==0)
return 0;
int index = 0;
int flag = 1;
StringBuilder temp = new StringBuilder();
while(index<str.length()&&str.charAt(index)==' ')
index++;
if(str.charAt(index)=='+')
index++;
else if(str.charAt(index)=='-')
{
index++;
flag = -1;
}
while(index<str.length()&&str.charAt(index)<='9'&&str.charAt(index)>='0')
{
temp.append(str.charAt(index));
index++;
}

if(temp.length()>10)
{
if(flag==1)
return Integer.MAX_VALUE;
else
return Integer.MIN_VALUE;
}

long p=0;
for(int i=0;i<temp.length();i++)
p = 10*p + temp.charAt(i)-'1'+1;
p = flag*p;
if(p>=Integer.MAX_VALUE)
return Integer.MAX_VALUE;
else if(p<=Integer.MIN_VALUE)
return Integer.MIN_VALUE;
else
return (int)p;
}
}