Palindrome class help in C++ [closed] - c++

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Hi i am trying to write a palindrome class but am getting the wrong results.
I need to create a Palindrome class and return whether the phrase is a Palindrome.
Here is my code.
Palindrome.h:
#ifndef PALINDROME_H
#define PALINDROME_H
#include <iostream>
#include<cstring>
using namespace std;
class Palindrome{
private:
char str[1024];
char s1[1024];
char s2[1024];
int a;
int b;
public:
Palindrome(char s2[1024], int a, int b)
{
s2[1024] = { 0 };
a = 0;
b = 0;
}
void removeNonLetters(char str[]);
void lowerCase(char s1[]);
bool isPalindrome(char s2[], int a, int b);
}; // End of class definition
#endif
Palindrome.cpp:
#include "Palindrome.h"
void Palindrome::removeNonLetters(char str[])
{
char s1[1024] = { 0 };
int j = 0;
int l1 = strlen(str);
for (int i = 0; i < l1; i++)
{
if (str[i] <= '9' && str[i] >= '0')
{
s1[j++] = str[i];
}
else if ((str[i] >= 'A' && str[i] <= 'Z')
|| (str[i]) >= 'a' && str[i] <= 'z')
{
s1[j++] = str[i];
}
}
cout << s1 << endl;
}
void Palindrome::lowerCase(char s1[])
{
char s2[1024] = { 0 };
int l2 = strlen(s1);
int g = 0;
for (int i = 0; i < l2; i++)
{
if (s1[i] >= 'a' && s1[i] <= 'z')
{
s2[g++] = s1[i];
}
else if (s1[i] >= 'A' && s1[i] <= 'Z')
{
s2[g++] = s1[i] + 32;
}
}
cout << s2 << endl;
}
bool Palindrome::isPalindrome(char s2[], int a, int b)
{
if (a >= b)
return true;
cout << "Yes" << endl;
if (s2[a] != s2[b])
return false;
else
return isPalindrome(s2, a + 1, b - 1);
cout << "No" << endl;
}
Main.cpp:
#include "Palindrome.h"
int main()
{
char str[1024] = { 0 };
char s1[1024] = { 0 };
char s2[1024] = { 0 };
cout << "input a string:" << endl;
cin.getline(str, sizeof(str));
Palindrome removeNonLetters(char str[]);
Palindrome lowerCase(char s1[]);
int length = strlen(s2);
Palindrome isPalindrome(s2, 0, length - 1);
return 0;
}

Answer 1

You teacher may not like this, but this is how we do it in the real world.
First things first, reach for the standard library:
#include <iostream>
#include <string>
#include <cstring>
#include <algorithm>
A function to strip non-alpha characters from a string:
std::string strip(std::string s)
{
s.erase(std::remove_if(std::begin(s),
std::end(s),
[](auto c) { return !std::isalpha(c); }),
std::end(s));
return s;
}
A function to transform a string to lower case:
std::string to_lower(std::string s)
{
std::transform(std::begin(s),
std::end(s),
std::begin(s),
[](auto c) { return std::tolower(c); });
return s;
}
A function to check that a string is the same in reverse as it is forwards:
bool is_palindrome(const std::string& s)
{
return std::equal(std::begin(s), std::end(s),
std::rbegin(s), std::rend(s));
}
Putting it all together in a test:
int main()
{
auto word = std::string("a!b B <>A");
if (is_palindrome(to_lower(strip(word)))) {
std::cout << "palindrome" << std::endl;
}
else {
std::cout << "not palindrome" << std::endl;
}
return 0;
}
Complete listing:
#include <iostream>
#include <string>
#include <cstring>
#include <algorithm>
std::string strip(std::string s)
{
s.erase(std::remove_if(std::begin(s),
std::end(s),
[](auto c) { return !std::isalpha(c); }),
std::end(s));
return s;
}
std::string to_lower(std::string s)
{
std::transform(std::begin(s),
std::end(s),
std::begin(s),
[](auto c) { return std::tolower(c); });
return s;
}
bool is_palindrome(const std::string& s)
{
return std::equal(std::begin(s), std::end(s),
std::rbegin(s), std::rend(s));
}
int main()
{
auto word = std::string("a!b B <>A");
if (is_palindrome(to_lower(strip(word)))) {
std::cout << "palindrome" << std::endl;
}
else {
std::cout << "not palindrome" << std::endl;
}
return 0;
}

Answer 2

There are many things wrong with your code. I hope these pointers help:
You should be using std library.
Why does the constructor for the class take any parameters? Nothign uses them
Why are there any member variables? Nothing uses them.
Why are the functions in a class at all? They're just functions - they should be in a functions library or similar.
The functions just write to cout so are useless.
Your main function doesn't even seem to call the functions correctly.
I tried this:
char str[1024] = { 0 };
cout << "input a string:" << endl;
cin.getline(str, sizeof(str));
int length = strlen(str);
Palindrome a(str,0, length);
a.removeNonLetters(str);
a.lowerCase(str);
a.isPalindrome(str, 0, length - 1);
cin.getline(str, sizeof(str));
return 0;
I don't get the exception but get the following output:
input a string:
EVIL rats on no star **** live
EVILratsonnostarlive
evilratsonnostarlive
Yes
However this works too:
input a string
hello
hello
hello
Yes
So the first two functions seem to work (if removing spaces was also intentional) but the third does not.