Copy char array in reverse to another char array

[thiemebr]

I've been trying to do this Palindrome program without succes...

It basically copy an string array backwards to another array and check if both are equal or not...

Where did I went wrong?

The code is:

#include <iostream>
#include <string.h>

using namespace std;

void main ()

{
char String[81];
char StringReverse[81];
int j(0);
int i(0);

cout << "Enter a string: ";
cin.getline(String,81);

cout << "\n\n";

while (String != '\0');
{
StringReverse[j] = String[i];
i++;
j++;
}

if (StringReverse[81] != String[81])
cout << "The string " << StringReverse << " is not a Palindrome" << "\n\n"<< endl;
else
cout << "Congratulations! The string " << String << " is a Palindrome" <<endl;

}

[Lindley]

while (String != '\0');
{
    StringReverse[j] = String[i];
    i++;
    j++;
}

What makes you think this loop will reverse the string? 'Cause it looks more like a simple copy to me. Also, the while condition is wrong---you probably meant while (String[ i ] != '\0').

if (StringReverse[81] != String[81])

If you're going to work with char arrays rather than std::strings, you have to use strcmp() to compare them---the above definitely won't do what you expect.

[thiemebr]

But I need to do this without using "str" methods....

[GCDEF]

His comments apply. Your code doesn't reverse a string, it copies it in the same order and your test for equality aside from not being how you compare strings, is looking at memory your app doesn't have access to.

Forgetting code for a minute, if you had to do it with a pencil and paper, how would you reverse a string?

[treuss]

But I need to do this without using "str" methods....

Then start with finding out, how long the string was that the user entered.

[thiemebr]

His comments apply. Your code doesn't reverse a string, it copies it in the same order and your test for equality aside from not being how you compare strings, is looking at memory your app doesn't have access to.

Forgetting code for a minute, if you had to do it with a pencil and paper, how would you reverse a string?

I would reverse a string by copying the last char of an array to the 1st position of another or duplicating the same array and comparing the 1st char of array1 to the last char of array2...

[Lindley]

Either approach will work. The second is probably slightly more efficient since it can be done on a single array without copying.

[GCDEF]

I would reverse a string by copying the last char of an array to the 1st position of another or duplicating the same array and comparing the 1st char of array1 to the last char of array2...

Is your code doing either of those?

[thiemebr]

Is your code doing either of those?

I'm doing the single array checking the string... but still not work....

[thiemebr]

I'm having problem to go to the end of the array and backward checking the string

[Lindley]

First things first: Find the length of the string and store it in a variable.

[thiemebr]

OK..Done

for (count = 0; letter[count]!='\0'; count++);

[Lindley]

Good. Given that, how would you compare the last character to the first? Forget the rest for the moment.

[thiemebr]

Going to the end of the array and doing the opposite of what I did

[Lindley]

Write an if statement which executes only if the first and last character are the same. It's one line.