Checking a palindrome using arrays

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  12 years ago

  by ronaldcampfaso

  Ronald Campfaso

  , Spain

  Joined 13 years ago

  Good day guys, Im having problems finding a palindrome using this code, hope somebody could lend me a hand, thanks a lot!

  Here's my code:

  #include <iostream>
  #include <string>
  using namespace std;
  
  int main () {
    char str[20];
    char rev[20];
    int i,z=0; 
    cout << "Please enter full name: ";
    cin.getline (str,20);
    i = strlen(str);
    for (z=0; z>=i; z++)
    {
       // Help here to get palindrome... thanks!
       rev= str[i-z];
       cout << "here" << rev;
    }
  
    return 0;
  }
  

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  12 years ago

  by Mohammad Rastkar

  Mohammad Rastkar

  Shiraz, Iran

  Joined 14 years ago

  If you want to check 'str' is a palindrome, here is a way :

  #include <iostream>
  #include <string>
  using namespace std;
  
  int main()
  {
      char str[7] = "123321",
          rev[7];
  
      strcpy(rev, str); // copy 'str' into 'rev'
      strrev(rev); // reversing 'rev'
  
      if (strcmp(str, rev) == 0)
          cout << "It's palindrome";
  
      return 0;
  }
  

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  12 years ago

  by ronaldcampfaso

  Ronald Campfaso

  , Spain

  Joined 13 years ago

   Mohammad Rastkar, thanks for the reply... The code runs in windows platform but the it does not work in a g++ compiler in ubuntu? The strrev is not recognized.  Is there any other way?

   I have a modifed code that gets the length and swap places to show reversal of text. The only problem is that what would be the statement for analyzing each character and then tells if it is a palindrome or not. Hope you could still help me... Thanks in advance!

  Here's my code:

   #include <iostream>
  #include <string>
  using namespace std;
  
  int main () {
    char str[20];
    char rev[20];
    int cc=0;
    int i,z=0;  
    cout << "Please enter a word: ";
    cin.getline (str,20);
    i = strlen(str);
    // places reverse string
    for (z=0;z<=i;z++)
    {
      rev = str[i-z];
    }  
    // displays original string
   cout << "Original message " ;
   for (z=0;z<=i;z++)
    {
       cout << str;
    }
    cout << endl;
    // displays reversed string
   cout << "Reversed message " ;
    for (z=0;z<=i;z++)
    {
       cout << rev;  
    }
  
    // I guess there should be if statements here
    cout << endl;
     return 0;
  }

   

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  12 years ago

  by Mohammad Rastkar

  Mohammad Rastkar

  Shiraz, Iran

  Joined 14 years ago

  Then use the following code snippet :

  #include <iostream>
  #include <string>
  using namespace std;
  
  int main()
  {
      char str[10] = "123404321";
      int len = strlen(str);
  
      int    mid = len/2, // middle of the string
          end = len-1;
  
      bool is_palindrome = true;
  
      for (int i = 0; i != mid; i++)
      {
          if (str[i] != str[end-i])
              is_palindrome = false; // not palindrome
      }
  
      cout << (is_palindrome ? "It's palindrome." : "it's not palindrome.") << endl;
  
      return 0;
  }
  

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