Thread: Stream question

I'm trying to make a program which reads in a digit and then a character, if there is no digit then it puts a 1 into cin so the 1 will be read as the digit. When I input "1a" I get the correct output but when I input "a" I get "a" as the digit and the character. What am I doing wrong?

Code:

#include <iostream>

using namespace std;

int main()
{
	cout << "start\n";
	char c;
	cin.get(c);
	if (!isdigit(c)) {
		cin.putback(c);
		cin.putback('1');
	} else {
		cin.putback(c);
	}

	cin.get(c);
	cout << "digit " << c << '\n';
	cin.get(c);
	cout << "letter " << c << '\n';
}

From
http://www.cppreference.com/cppio/putback.html:

The putback() function is used with input streams, and returns the previously-read character ch to the input stream.

The "previously-read" character, not any character you choose. Anyway, why are you trying to push a character onto the input stream? Why not just print your default digit if a digit is not read from cin?

would probably be easier to read the whole thing into a string and go from there

Code:

string s;
cin >> s;
if (!isdigit(s.at(i))) {
     cout << 1;
}
cout << s << endl;

only upto the first whitespace

That is what I meant by the "whole string" not the "whole line".