How to check for non-integer input in multiple inputs - c++

Question

I was working on this program for a while and I can not find a way to make the cin.fail() output "Incorrect input." on 2nd,3rd,4th,... digit of the second binary number. For example "11111 a11" is detected as input fail but "11111 1a1" or "11111 1abfcds" is not detected. It seems to only check the 1st digit. Here is the program.
#include <iostream>
#include <cmath>
using namespace std;
int binary_decimal_1(int n);
int binary_decimal_2(int m);
int decimal_binary(int s);
int main()
{
int n, m, s;
cout << "Input 2 binary numbers" << endl;
cin >> n;
if (cin.fail())
{
cout << "Incorrect input." << endl;
return 0;
}
cin >> m;
if (cin.fail())
{
cout << "Incorrect input." << endl;
return 0;
}
s= binary_decimal_1(n) + binary_decimal_2(m);
cout << "Sum: " << decimal_binary(s) << endl;
return 0;
}
int decimal_binary(int s) /* Function to convert decimal sum to binary result.*/
{
int rem, i=1, binary=0;
while (s!=0)
{
rem=s%2;
s/=2;
binary+=rem*i;
i*=10;
}
return binary;
}
int binary_decimal_1(int n) /* Function to convert binary number 1 to decimal.*/
{
int decimal_1=0, i=0, rem;
while (n!=0)
{
rem = n%10;
n/=10;
decimal_1 += rem*pow(2,i);
++i;
}
return decimal_1;
}
int binary_decimal_2(int m) /* Function to convert binary number 2 to decimal.*/
{
int decimal_2=0, i=0, rem;
while (m!=0)
{
rem = m%10;
m/=10;
decimal_2 += rem*pow(2,i);
++i;
}
return decimal_2;
}

Answer 1

Input processing terminates on the first non-numeric character encountered.
Once you get a value to parse, use a function to validate it:
template <typename T>
bool convert_to( const std::string& s, T& value )
{
std::istringstream ss( s );
ss >> value >> std::ws;
return ss.eof();
}
--Typed off the top of my head; typos may have occurred.

Answer 2

I fixed my program by using strings and checking those for incorrect input, converting strings to integers and now it works.
#include <iostream>
#include <cmath>
#include <sstream>
using namespace std;
int binary_decimal_1(int n);
int binary_decimal_2(int m);
int decimal_binary(int s);
int main()
{
string n, m;
int s;
cout << "Input 2 binary numbers:" << endl;
cin >> n;
cin >> m;
bool bValidn = true; // Function to check for non numeric input in n.
for (unsigned int nIndex=0; nIndex < n.length(); nIndex++)
if (!isdigit(n[nIndex]))
{
bValidn = false;
cout << "Bad input.";
return 0;
}
bool bValidm = true; // Function to check for non numeric input in m.
for (unsigned int nIndex=0; nIndex < m.length(); nIndex++)
if (!isdigit(m[nIndex]))
{
bValidm = false;
cout << "Bad input.";
return 0;
}
// Now to convert strings into integers.
int intn;
stringstream convertn(n);
if ( !(convertn >> intn) )
intn = 0;
int intm;
stringstream convertm(m);
if ( !(convertm >> intm) )
intm = 0;
// And the hardest part.
s = binary_decimal_1(intn) + binary_decimal_2(intm);
cout << "Sum is: " << decimal_binary(s) << endl << endl;
return 0;
}
int decimal_binary(int s) // Function to convert decimal sum to binary result.
{
int rem, i=1, binary=0;
while (s!=0)
{
rem=s%2;
s/=2;
binary+=rem*i;
i*=10;
}
return binary;
}
int binary_decimal_1(int intn) // Function to convert binary number 1 to decimal.
{
int decimal_1=0, i=0, rem;
while (intn!=0)
{
rem = intn%10;
intn/=10;
decimal_1 += rem*pow(2,i);
++i;
}
return decimal_1;
}
int binary_decimal_2(int intm) // Function to convert binary number 2 to decimal.
{
int decimal_2=0, i=0, rem;
while (intm!=0)
{
rem = intm%10;
intm/=10;
decimal_2 += rem*pow(2,i);
++i;
}
return decimal_2;
}