C++ int转string string转int 完美实现

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

int str2int(const string& word) {
int Sum = 0;
string temp = word;
while (temp != "") {
Sum *= 10;
Sum += temp[0] - '0';
temp = temp.substr(1);
}
return Sum;
}

string int2str(const int& num) {
ostringstream out;  //#include <sstream>
out << num;
return out.str();
}

//==============test=================
int main() {
cout<<int2str(100)<<endl;
cout<<str2int("200")<<endl;

}