Over looping (Cout) in C++ - c++

Question

#include <iostream>
#include <string>
#include <cctype>
using namespace std;
char hold;
string name;
char num1;
char num2;
int main() {
cout << "Hello!\n";
cout << "Tell me your name?: ";
cin >> name;
cout << "Well well well, if it isn't "<< name << "!\n";
cout << "Enter a NUMBER " << name << ": ";
cin >> num1;
while(!isdigit(num1)) {
cout << "Enter a NUMBER " << name << ": ";
cin >> num1;
}
cin >> hold;
system("pause");
return 0;
}
The problem is, it is overlooping the cout. How do I fix it?
Thanks.

Answer 1

A better way is to use std::stringstream (note: include sstream)
int getNumber()
{
std::string line;
int i;
while (std::getline(std::cin, line))
{
std::stringstream ss(line);
if (ss >> i)
{
if (ss.eof())
{
break;
}
}
std::cout << "Please re-enter your input as a number" << std::endl;
}
return i;
}
This replaces your while loop, and you make the call after asking for a number as you already figured out how to do.

Answer 2

The following is a shortened version of the original attempt. However, as with the original, it only checks a single character.
If I changed num1 to be an int then i'd need to check whether the input was valid as #Dieter Lucking mentioned.
#include <iostream>
using namespace std;
int main() {
char num1;
do {
cout << "\nEnter a number: ";
cin >> num1
} while(!isdigit(num1));
}

Answer 3

A bit of a variation on staticx's solution, which will pass Dieter Lücking's echo "" | test line.
I use an istringstream and get input until no more standard input or I get valid input. I pushed it all into a templated Get function that can be used for any type; you just need to give it a prompt for the user:
Get() function
template<typename T>
void Get(T& toSet, std::string prompt) // read from cin
{
std::string nextIn;
cout << prompt;
getline(cin >> std::ws, nextIn);
istringstream inStream(nextIn);
while(cin && !(inStream >> toSet))
{
inStream.clear();
cout << "Invalid Input. Try again.\n" << prompt;
getline(cin >> std::ws, nextIn);
inStream.str(nextIn);
}
if (!cin)
{
cerr << "Failed to get proper input. Exiting";
exit(1);
}
}
And you'd use it like so:
int myNumber = 0;
Get(myNumber, "Please input a number:");
Full code:
Live Demo
#include <iostream>
#include <string>
#include <sstream>
using namespace std;
template<typename T>
void Get(T& toSet, std::string prompt) // read from cin
{
std::string nextIn;
cout << prompt;
getline(cin >> std::ws, nextIn);
istringstream inStream(nextIn);
while(cin && !(inStream >> toSet))
{
inStream.clear();
cout << "Invalid Input. Try again.\n" << prompt;
getline(cin >> std::ws, nextIn);
inStream.str(nextIn);
}
if (!cin)
{
cerr << "\nFailed to get proper input. Exiting\n";
exit(1);
}
}
int main()
{
string name;
int num1 = -1;
cout << "\nHello!\n";
Get(name, "\nTell me your name?:");
cout << "\nWell well well, if it isn't "<< name << "!\n";
Get(num1, std::string("\nEnter a NUMBER, ") + name + ": ");
cout << "\nYou entered number: " << num1 << std::endl;
return 0;
}