Thread: Pailindrome Function and Reverse Fucntion Problem

Actually I was supposed to make a program to check for a entered string that weather its a palindrome or not, I wanted to make a function isPal() but it all jinxed and im all confused where to start and how to work on it, Actually I know that this program is not a difficult task if I'd have used string.h header file, but I want to take inputs character by character, and output as string ... I thought that it would be easy but it blew my head, but now I'm more stuck on it to only do it this way or find a solution of this way character-by-character.

It seems like my approach to this problem is kinda wrong, please correct me, or suggest me any idea soon ...

For the mean time, here's my incomplete effort:

Code:

#include<stdio.h>
#include<conio.h>
#define LIM 	100
#define TRUE 	1


void StRev(char array[],char array2[])
{
   int c,x;
   while(array[c]!='\0')
	 ++c;

   	for(x=0;x<c;x++)
   	{
     	array2[x]=array[c-x];
 	  }
}

int isPal(char arr2[])
{
   char ch[LIM];
   StRev(ch);

   if(ch==arr2)
     return 1;
   else
     return 0;


}
int main()
{
    char In[LIM],out[LIM];
    int count=0;
    printf("Enter a String: ");
    while( In[count] != '\x0D' );
    {
       In[count++]=getche();
     }


     if(isPal(In)==1)
       printf("yes");
     else
       printf("No");
 return 0;
}

Originally Posted by joshdick

The equality operator (==) is not defined for arrays of characters. Use strcmp() to compare strings.

Also, you can use strlen() to get the length of a null-terminated string.

It looks like you ought to get to know the <string.h> library.

Actually I wanted to do it manually, without using stings.h header file ... I have said this above ... and its also probably on bold ....

Originally Posted by joshdick

Sorry I missed that. In that case, I suggest just implementing your own versions of those functions.

For the function to reverse a string, your logic is wrong. You need to swap the characters. First, the first and last characters; then, the second and second to last characters; etc.

Here's the code but its still not working ...

Code:

#include<stdio.h>
#include<conio.h>
#define LIM 	100
#define TRUE 	1

void swapCh(char var1,char var2)
{
   char temp;
      temp=var1;
      var1=var2;
      var2=temp;
}

void StRev(char array[],char array2[])
{
  char  ch;
  int   count=0;
  int   x,y;

    while(array[count] != '\0')
	 ++count;

    for(x=count,y=0;x<count;x--,y++)
	swapCh(array[y],array2[x]);


}

int isPal(char arr2[])
{
   char ch[LIM];
   StRev(arr2,ch);

   if(ch==arr2)
     return 1;
   else
     return 0;


}
int main()
{
    char In[LIM],out[LIM];
    int count=0;
    clrscr();
    printf("Enter a String: ");
    while( In[count++] != 13 )
    {
       In[count]=getche();
     }
     StRev(In,out);
     printf("\n%s",out);

     if(isPal(In)==1)
       printf("\nyes");
     else
       printf("\nNo");
 return 0;
}

Originally Posted by Stoned_Coder

you cant compare strings that way you need to use strcmp() to compare strings. look it up in your helpfiles.
Other than that this has been covered many times do a board search.

im not doing string comparison, im doing comparison character by character ...

Code:

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int is_palindrom(char niz[]);

int main(int argc, char *argv[])
{
  if(argc<2)
    { 
      printf("Need an argument-a word!\n");
      exit(1);
    }

  if(strlen(argv[1])==0 || strlen(argv[1])==1)
    { printf("input a word not a character!\n");
    exit(1);
    }

  if(is_palindrom(argv[1])==0)
    {
      printf("A word %s is palindrom!\n",argv[1]);
    }

  else printf("Not a palindrom!\n");
 
}

int is_palindrom(char niz[])
{
  char reverse_niz[strlen(niz)];
  int i;
  int x=0;
  for(i=strlen(niz)-1;i>=0;i--)
    {
      reverse_niz[x]=niz[i];
      x++;
    }
  reverse_niz[x]='\0';
     
  if(strcmp(reverse_niz,niz)==0)
    return 0;

  else 

    return 1;

}