Palindrome in C (Please try my code)

[Kontilera]

Homework Statement

Make a code that can check if one or many words are palindromes.

The Attempt at a Solution

I can't get my compiler to work so I wrote my attempt in a note document. Please can you check if it works and if it doesn't give me some guidence.. I have put a lot of time into the problem and now I thought I was finished but my computer stops working.

I suspect that I have missused strtok() but "," should separate the words.
Thanks.

#include <stdio.h>
#include <string.h>
 
main()
{
   i=1;
   char words[100], invers[100], word[50];		
 
   printf("Please write your words:\n");
   gets(words);					
 
   word= strtok(words, ,);
while(word != NULL){

   strcpy(invers,word); 				
   strrev(invers);				
 
   if( strcmp(word,invers) == 0 )		
      printf("%s - Palindrome!\n", ord );
   else
      printf("%s Not Palindrome!\n", ord );}

   return 0;

 

[Mark44]

Homework Statement

Make a code that can check if one or many words are palindromes.

The Attempt at a Solution

I can't get my compiler to work so I wrote my attempt in a note document. Please can you check if it works and if it doesn't give me some guidence.. I have put a lot of time into the problem and now I thought I was finished but my computer stops working.

I suspect that I have missused strtok() but "," should separate the words.
Thanks.

#include <stdio.h>
#include <string.h>
 
main()
{
   i=1;
   char words[100], invers[100], word[50];		
 
   printf("Please write your words:\n");
   gets(words);					
 
   word= strtok(words, ,);
while(word != NULL){

   strcpy(invers,word); 				
   strrev(invers);				
 
   if( strcmp(word,invers) == 0 )		
      printf("%s - Palindrome!\n", ord );
   else
      printf("%s Not Palindrome!\n", ord );}

   return 0;

As you suspected, you aren't using strtok correctly. If you want to specify that the separator is a comma, call it like this:

pChar = strtok(words, ",");

Here, pChar is declared as a pointer to char; i.e., char * pChar;

Here's a link to some documentation: http://www.cplusplus.com/reference/clibrary/cstring/strtok/

You have several other problems.
1. In this code,

word= strtok(words, ,);

the word variable cannot appear on the left side of an assignment statement. Since it is declared as an array of char, its value (an address) is constant. That's why I used a pointer in my code above.
2. In this code,

while(word != NULL)

you will have an infinite loop, since word never becomes null (as already mentioned, its value is constant).
3. There are a few syntax errors, such as missing brace at end of main function, and an undeclared variable (ord).

 

[Kontilera]

Ah thanks Mark44! Yeah, I see that I made some misstakes when I tried to translate the code to english for you.

Ah strtok returns a pointer.. maybe this would work then:

#include <stdio.h>
#include <string.h>
 
main()
{
   char words[100], invers[100], word[40], *pchar;		
 
   printf("Please type your words:\n");
   gets(words);				
 
   pchar = strtok(words, ",");
while(pchar != NULL){
   word = *pchar
   strcpy(invers,word); 				
   strrev(invers);				
 
   if( strcmp(word,invers) == 0 )		
      printf("%s - Palindrome!\n", word );
   else
      printf("%s Not Palindrome! \n", word );}
}
   return 0;

 

[Mark44]

I see a couple of problems with this attempt, one of which would generate a compile-time error.
1. Syntax error. word cannot appear on the left side of an assignment statement. This will result in a compiler error. To fix it, use strcpy to copy the characters pointed to by pchar to the word array.
2. Semantic error. Your loop will either run 0 times (if there is no comma in words) or forever. Assuming you found a comma in words, pchar is set with that address. The next iteration of the loop, pchar still has the same address, so the loop runs again. And so on.

 

[jbunniii]

What if I type a word with 101 characters in it?