string to integer?

After testing the user input and confirming contains only numbers, how do I convert the string to an integer. Have spent hours attempting to do so, obvoisly without success....

Or change the code below to accept an integer and test...?
#include <iostream>
#include <cstring>
#include <string>
#include <cctype>

using namespace std;

int main()
{
string answer;
char again;
do
{
cout << "Enter a number or letter ";
cin >> answer;
for (int i = 0; i < answer.length(); i++)
{
if (!isdigit(answer[i]))
{
cout << answer << " is not a number!" << endl;
break;
}
}
cout << "\nAnswer is " << answer << endl;
cout << "more> ";
cin >> again;
}while(again == 'y');
return 0;
}

Code:

---

#include <iostream>
#include <string>
#include <cctype>
#include <sstream>

using namespace std;

int main() {
        cout << "Please enter an integer: " << flush;

        int num;
        cin >> num;
        cout << endl;

        if(cin.fail()) {
                cout << "You didn't enter a number!" << endl;
                return -1;
        }

        cout << "Final number: " << num << endl;

        return 0;
}

---

:)

Similar to yours but I tweaked it for a more C++-like style ;)

Quick note - if you enter too large a number it overflows and the internal stream sets the fail bit.

Radix lecti :D mmm?

couch potato *** laude :D

One does one's best :D

PS: Just as well the server went strange earlier; saved me posting the earlier version involving the original isdigit() loop to verify the string.... :eek: *shudder*

much gratitude!!!!!

Still need help with a slight tweak....

If I enter 8r33 it accepts the entry as 8.

The ultimate would be the entire entry must me numeric....however, what I have now is alot more than what I had.

If there is a simple tweak to check the entire entry, well that would make my semester!!!!!!!

Code:

---

#include <iostream>
#include <string>
#include <sstream>

using namespace std;

int main() {
        cout << "Please enter an integer: " << flush;

        int num;
        cin >> num;
        cout << endl;

        // get the rest of the stream
        string s;
        getline(cin, s);

        if(!s.empty() || cin.fail()) {
                cout << "You didn't enter a number!" << endl;
                return -1;
        }

        cout << "Final number: " << num << endl;

        return 0;
}

---

The getline in the middle extracts what's left on the input line, since the cin >> num has only extracted the first numeric portion it can. If it goes straight to a newline, then the string will be empty since no extra characters were present.