int myAtoi(string str) {
if (str.size() == 0)return 0;
long num = 0;
int flag = 1;
int index = 0;
for (size_t i = 0; i < str.size(); ++i)
{
if (str[i] == ' ')
{
if (index == 0)
{
continue;
}
else
break;
}
else if(str[i]=='+'&&index==0)
{
index=1;
continue;
}
else if (str[i] == '-')
{
if(index==0)
{
index=1;
flag=-1;
continue;
}
else
break;
}
else if (str[i] < '0' || str[i]>'9')
{
if(index ==0)
return 0;
else
{
index = 1;
break;
}
}
else
{
num = num * 10 + str[i] - '0';
index = 1;
}
if (num*flag > INT_MAX)
return INT_MAX;
if (num*flag < INT_MIN)
return INT_MIN;
}
return num*flag;
}
