Testing if a number is a Palindrome using different functions (C++) - c++

Question

The code I am using is:
#include <iostream>
using namespace std;
int reverse (int number){
int t = number, m = 0;
do
{
m = m*10 + t%10;
} while(t /= 10);
return m == number;
}
bool isPalindrom(int number){
bool Palindrom = reverse(number);
if(Palindrom == true){
return true;
} else {
return false;
}
return 0;
}
int main()
{
int number;
cout << "Please input a number " << endl;
cin >> number;
if(isPalindrom){
cout << "This is a Palindrom" << endl;
} else {
cout << "This is not a Palindrom" << endl;
}
}
The issue I am having is that isPalindrom is always evaluating to true. I believe it is because I am trying to set this up incorrectly. The program asks us to use the two functions bool isPalindrom(int number) and int reverse(int number). I'm just learning to use functions in C++ so i'm not to sure what I should do. Should I have reverse return the numbers flipped self (m) then in palindrom compare number to m and if it evaluates to true, it will return true. Then in the main check with an if statement to see if isPalindrom is true/false.

Answer 1

You are not calling the function correctly.
if(isPalindrom){
cout << "This is a Palindrom" << endl;
} else {
cout << "This is not a Palindrom" << endl;
}
To call it you have to supply a parameter like this
if (isPalindrom(number)) {
....
In your code isPlanindrom is (I believe, but actually it does not matter if I am right on this point) a function pointer and because it is in the condition of if it gets converted to a bool, which is true always.
PS: I just noticed that I was too fast in writing the answer. I just saw this one problem and didnt look at the rest of the code. It seems like you need to learn about very basics which would be too much to cover here in an answer. My suggestion: Get a book and rtfm :P

Answer 2

In main, you are evaluating the existence of a function called isPalindrom; you aren't actually calling the function. if(isPalindrom){ should become if(isPalindrom(number)){.

Answer 3

You forget to call isPalindrom with an argument. Here's the fix:
#include <iostream>
using namespace std;
bool reverse (int number){
int t = number, m = 0;
do
{
m = m*10 + t%10;
} while(t /= 10);
return m == number;
}
bool isPalindrom(int number){
return reverse(number);
}
int main()
{
int number;
cout << "Please input a number " << endl;
cin >> number;
if(isPalindrom(number)){
cout << "This is a Palindrom" << endl;
} else {
cout << "This is not a Palindrom" << endl;
}
}
I've also:
simplified your isPalindrom() function to a simple return statement;
set the return of reverse from int to bool.
You can try a LiveDemo

Answer 4

Short answer: you forgot to call isPalindrom.
Long answer: isPalindom decays to a nonnull function pointer, and nonnull pointers test true, this you always see the the if branch taken.
Also:
Yes, judging both by the name and the return type, reverse is intended to return the reverse of a number.
And correspondingly, it is the job of isPalindom to do the actual comparisons.
Furthermore, in most cases,
if (boolean) { return true; }
else { return false; }
should be replaced with
return boolean;
Finally, you really ought to be testing whether or not cin succeeded and your input is valid. (e.g. is the user allowed to enter 0? -73? Zero?)