Errors that I cannot figure out

I am getting a couple of errors when I compile this program and all I seem to be doing today is making them worse.
This program is a homework program that I did before and it worked, but my program structure was totally different. I am re-writing it again as a class(we are working about classes , structs, inheiritance etc., and I wanted to try out this new material on a program that I had done before), but have screwed up in my functions and am just confused now. I know this is a case of messing with it for too long and the more I try to correct it the more I am messing it up.

Code:

---

#include <string>
#include <iostream>
using namespace std;

class PString : public std::string
{
public:
        PString( const std::string &aString );
        bool isPalindrome() const;
};

PString::PString( const std::string &aString ) : std::string( aString )
{

}
bool PString::isPalindrome() const
{
string reverse(string word)
{
string reverse;
int length=word.length();
for(int i=length;i>=0;i--)
{
reverse=reverse+word[i];
}
return reverse;
}
bool pal(string word)
{
bool pal=true;
if(word!=reverse(word))
{
pal=false;
}
return pal;
}
        return true;
}

int main()
{
        std::string str;
        std::cout << "This program is a palindrome-testing program. Enter a string to test:\n";
        std::cin >> str;

        // Create a PString object that will check strings
        PString s(str);

        // Check string and print output
        if (s.isPalindrome())
        {
                std::cout << s << " is a palindrome";
        }
        else
        {
                std::cout << s << " is not a palindrome";
        }
        std::cout << std::endl;
        system("pause");
        return 0;
}

---

Specifically, I am getting error code C2601 on line string reverse(string word) and bool pal(string word).
I get error C2780 two lines below that line and it tells me there is a problem in the void function- but I have no void function.
What do I need to look at to get this to work? (Besides aspirin and a stiff drink!)

As a general rule, mentioning error codes is useless. It would be much more helpful to quote the exact error message (indicating, of course, which line of code it relates to whenever possible).

In this case the problem is that you are defining a function -- isPalindrome -- and inside the definition of that function you are trying to define two more functions: reverse and pal.

You can't define one function inside another, so define the functions reverse and pal as member functions of the class, and then if you want you can use them (call them) inside other functions.

edit: Also, it's not a good idea to declare a variable named reverse inside the function which is also named reverse, or a variable named pal inside the function named pal. Give the variables names that distinguish them from the functions.

I don't think STL (container) classes are designed to be inherited from. PString could contain a std::string as a data member but should not be derived from one.

Please look into indenting your code. It would certainly make it much easier to read. Like this:

Code:

---

#include <string>
#include <iostream>
using namespace std;

class PString : public std::string
{
public:
    PString( const std::string &aString );
    bool isPalindrome() const;
};

PString::PString( const std::string &aString ) : std::string( aString )
{

}
bool PString::isPalindrome() const
{
    string reverse(string word)
    {
        string reverse;
        int length=word.length();
        for(int i=length; i>=0; i--)
        {
            reverse=reverse+word[i];
        }
        return reverse;
    }
    bool pal(string word)
    {
        bool pal=true;
        if(word!=reverse(word))
        {
            pal=false;
        }
        return pal;
    }
    return true;
}

int main()
{
    std::string str;
    std::cout << "This program is a palindrome-testing program. Enter a string to test:\n";
    std::cin >> str;

    // Create a PString object that will check strings
    PString s(str);

    // Check string and print output
    if (s.isPalindrome())
    {
        std::cout << s << " is a palindrome";
    }
    else
    {
        std::cout << s << " is not a palindrome";
    }
    std::cout << std::endl;

    system("pause");

    return 0;

}

---

You are defining your function reverse within another function, which is not allowed.

C2601: 'function' : local function definitions are illegal

in other words, nested functions are not allowed in C++. you can make 'reverse' and 'pal' private member functions then call them in isPalindrome.

Quote:

---

Originally Posted by hk_mp5kpdw

I don't think STL (container) classes are designed to be inherited from. PString could contain a std::string as a data member but should not be derived from one.

---

The biggest problem of deriving from STL classes is that they tend to keep their members private, and not protected. It's not like it's bad, more like impracticable, I would say.
Still, I am unsure if there are any good arguments against deriving from them.