Palindromes

**laserlight** · 02-22-2009

What is your current code? It looks like you are defining reverse twice, or there is a conflict with the standard library version.

**jewelz** · 02-22-2009

everything in my last post is my current code...i didn't change anything from that..

**laserlight** · 02-22-2009

Oh, I see the problem now:

Originally Posted by jewelz

and as for the main function i posted above i included "pal.h" and "pal.cc" and then the appropriate declarations and usings..what might be the problem?

You should not be including "pal.cc". You should compile pal.cc separately and link it with the object file produced by compiling main.cc (or whatever source file the main function is in).

Instead of including <iostream> in pal.h, include <string> since you refer to std::string in pal.h.

**jewelz** · 02-22-2009

Originally Posted by laserlight

Oh, I see the problem now:

You should not be including "pal.cc". You should compile pal.cc separately and link it with the object file produced by compiling main.cc (or whatever source file the main function is in).

Instead of including <iostream> in pal.h, include <string> since you refer to std::string in pal.h.

so i dont have to include "pal.cc" anywhere?

**laserlight** · 02-22-2009

Yes.

**jewelz** · 02-22-2009

ok well this is what i came up with for printing the the palindromes:

Code:

int main()
{

    string s;
    
    while(cin >> s){
	if(isPalindrome(s)== true)
	    cout << s << endl;

    }
return 0;

}

now for the last part, the program will take input and output the longest palindrome, along with its length..i came up with this:

Code:

int main()
{

    string s;
    vector<string> words;
    
    while(cin >> s) && (isPalindrome(s)== true)
			{
			    words.push_back(s);
			}
    string longest = words[0];

    for (int i = 1; i != words.size(); i++) {
	if(words[i].length() > longest.length()) {
	    longest = words[i];
	}

	cout <<"Longest Palindrome is " << "\"" << longest << "\""
	     << "whose length is " << longest.length() << endl;

    
	return 0;

    }

does this seem ok?

**vart** · 02-22-2009

you do not need to store all the strings to find the longests

enogh to have 2 strings - longest_so_far and current

**jewelz** · 02-22-2009

um..can u explain that a little more please? my method wouldn't output the longest palindrome?

**tabstop** · 02-22-2009

It would, eventually. But you don't need to store all the words, just the longest (unless you need to keep all the palindromes for other reasons).

**jewelz** · 02-22-2009

ok is this better??

Code:

int main()

{
typedef string:: size_type string _size;

string s;
string_size max = s.size();
string longest = s;
    
    while(cin >> s) && (isPalindrome(s)== true) {
	string_size size = s.size();
            if (size > max) {
               max = size;
              longest = s;
        }

}
   
   cout <<"Longest Palindrome is " << "\"" << longest << "\""
	     << "whose length is " << max << endl;

    
	return 0;

}

**m37h0d** · 02-22-2009

you've got erroneous spaces in your typedef.

**jewelz** · 02-22-2009

Code:

typedef string::size_type string_size;

is everything good now?? =)

**m37h0d** · 02-22-2009

that looks good

**m37h0d** · 02-22-2009

incidentally,i think it's very odd you weren't encouraged to do something like this:

Code:

bool isPalindrome(const std::string& s)
{
     std::string::const_iterator fit = s.begin();
     std::string::const_iterator rit = s.end();
     --rit;
     for(unsigned int i=0;i<s.size()/2;i++,fit++,rit--)
     {
        if(*fit==' ')
            ++fit;
        if(*rit==' ')
            --rit;
        if(*fit != *rit)
         return false;
     }
     return true;
}