#include <cassert>
#include <iostream>
#include <sstream>
using namespace std;
int main()
{
stringstream buffer;
int onechar; // because char cannot represent EOF
cout << "Enter some text: ";
while ( ( onechar = cin.get() ) != EOF ) {
if ( onechar == '\n' ) {
break; // exit loop at the end of the line
} else if ( isalpha( onechar ) ) {
buffer << "alpha: " << char( onechar ) << '\t' << onechar <<'\n';
} else if ( isdigit( onechar ) ) {
buffer << "digit: " << char( onechar ) << '\t' << onechar <<'\n';
} else {
buffer << "other: " << char( onechar ) << '\t' << onechar <<'\n';
}
}
cout << buffer.str() << '\n'; // str() returns string
return 0;
}