need help with the c programming code?

fm_hyudin · 09-10-2008, 03:30 AM

I already did overall coding for this question but i don't understand last statement saying [Enter a five-digit number ( -1 to end ): -1].Can anyone plz tell me and edit my coding for me plz.Thanks alot for your help.

Code:

#include <stdio.h> 
#include <string.h> 

#define TRUE 1 
#define FALSE 0 

main () { 

char str[30]; 
int isPalindrome = TRUE; 
int i,j; 


printf("Enter a five-digit number : "); 
gets(str); 
j = strlen(str) - 1; 
i = 0; 


while(i <= j && isPalindrome) { 

if(str[i] != str[j]) { 
isPalindrome = FALSE; 
} 
i++; 
j--; 
} 

if(isPalindrome) { 
printf("%s is a palindrome!\n", str); 
} 
else { 
printf("%s is not a palindrome\n", str); 
} 
return 0; 
}

Question 1

A palindrome is a number or a text phrase that reads the same backward as forward. For example, each of the following five-digit integers is a palindrome: 12321, 55555, 45554 and 11611. Write a program that reads in a five-digit integer and determines whether or not it is a palindrome. [HINT: Use the division and remainder operators to separate the number into its individual digits.]
(5 marks)

Sample output:

Enter a five-digit number ( -1 to end ): 18181
18181 is a palindrome

Enter a five-digit number ( -1 to end ): 16738
16738 is not a palindrome

Enter a five-digit number ( -1 to end ): -1

chrism01 · 09-10-2008, 03:47 AM

Seeing as you've already written some code.. I think the Sample output implies (!) that your prog should be an infinite loop that repeatedly asks for a number to test, and only exits if you give it the value '-1' to test.

billymayday · 09-10-2008, 03:52 AM

It also gives a pretty strong hint to read the input as an integer, not a string, so you may want to comply.

I wouldn't use an infinite loop though, I'd use use a while/do loop and test the input at the start.

fm_hyudin · 09-10-2008, 03:57 AM

thanks for the help.any more guidance on where i should adjust the codes plz?

billymayday · 09-10-2008, 04:00 AM

Did you write that code yourself? Surely you know enough to do a loop with a simple test. If not, you should if you expect to pass.

chrism01 · 09-10-2008, 08:10 PM

@billy, y I was a bit loose with the word 'infinite' there

Your soln is basically what I meant.