Recognize "010" and similar numbers as a palindrome using modulus in C++ - c++

Question

First post! This is my second semester with "Advanced C & C++" so any help is GREATLY appreciated. I've already scoured as much of stackoverflow and a few other resources to try and help me understand what I'm doing (or not doing) with this slew of logically inept code.
The goal of this program is to recognize whether or not a 'number' given by the user is a palindrome. Sounds simple enough right?! Ugh...well this is what I have been stuck on:
#include <iostream>
using std::cout;
using std::cin;
#include <string>
using std::string;
#include <cstdlib>
int main()
{
//variable declarations
string buffer;
//user input
cout << "Enter a number to see if it is a palindrome[Q to quit]: ";
getline(cin, buffer);
//looooop
while(buffer != "Q" && buffer !="q")
{
int userNum, length, sum = 0, temp;
userNum = atoi(buffer.c_str());
for(temp = userNum; userNum !=0; userNum=userNum/10)
{
length = userNum % 10;
sum = sum*10+length;
}
if(temp==sum)
cout << temp << " is a palindrome!!\n\n";
else
cout << buffer << " is NOT a palindrome!\n\n";
cout << "Enter a number to see if it is a palindrome[Q to quit]: ";
getline(cin, buffer);
}
}
The problem arises when input of "010", or "400" is given. "400" is essentially "00400" in this case and both should be seen as a palindrome.

Answer 1

A better approach would be to get trailing zeros for the given number as below:
int noOfTrailingZeros = str.length;
while(str[--noOfTrailingZeros]=='0');
noOfTrailingZeros = str.length - noOfTrailingZeros;
Or the integer way as:
int noOfTrailingZeros = str.length;
while(num%10==0)
{
noOfTrailingZeros++;
num/=10;
}
Now, check for the input string whether it has the same number of zeros befire the number or not as:
int counterZeros = 0;
while(str[counterZeros++]=='0');
check these 2 numbers and if trailing zeros are more than the zeros at beginning, add that many at the beginning and pass that string to palindrome function.

Answer 2

First of all, to recognize a palindrome, you don't have to do atoi. Just pass from the start to the middle checking if
buffer[i] == buffer[length - i]
Second, use the atoi to make sure it is a number and you're done.
Other way is to compare the string with itself reversed:
string input;
cout << "Please enter a string: ";
cin >> input;
if (input == string(input.rbegin(), input.rend())) {
cout << input << " is a palindrome";
}