【LeetCode笔记】Reverse Integer

1. If want to reuse the same stringstream object, need to clear the buffer before use. 

stream.clear() works in Dev-C++. 

Others recommended stream.str(""), but it doesn't work in my code.

2. int: 10, 100, 1000, 10000...

After being converted to string type and reversed, they'll be 01, 001, 0001, 00001... Convert them back to int, will get just 1, no more zeros.

3. reverse int : 1000000003 can cause overflow problem.

So use long long type to save 3000000001. Problem solved.

4. Assignment: string = int will assign the ACSii code of the int to string. e.g.:

int i = 49; string s = i; cout << s;

Output: 1

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My test code:

#include<iostream>
#include<string>
#include<sstream>
#include<algorithm>
using namespace std;


int main(){

int i = 1000000003;
string s;
stringstream ss;

s = i;
cout << i << " " << s << endl;

// int to string
ss << i;
ss >> s;
cout << i << " " << s << endl;

// reverse string 
reverse(s.begin(), s.end());
cout << sizeof(s) << " This is a string " << s << endl;

// string to in
long long result;
ss.clear();
ss << s;
ss >> result;
cout << sizeof(result) << " This is a int " << result << endl;

return 0;
}