palindrome of number in C - c

Question

#include<stdio.h>
int main(void)
{
int rev=0,temp=0,frwd,n,ans=0;
int i,j;
for(i=100;i<=999;i++)
{
for(j=i;j<=999;j++)
{
n = i*j;
frwd = n;
while(n!=0)
{
temp = n%10;
n = n/10;
rev = temp+rev*10;
}
printf("%d",rev);
if((rev == frwd)&&(ans<frwd))
{
ans=frwd;
printf("%d",ans);
}
}
}
return(0);
}
I have tried working out everything but this code doesn't seem to give the correct output.
The desired output is largest palindrome number of 6 digits.
If I am running the individual parts i.e. the reversing of number , checking of number whether or not it is a palindrome or the for loops, they are working fine but in the program they are giving garbage as output.
Any help would be appreciated.

Answer 1

ya the problem is that you are not reinitializing rev to 0 as said by cowanother.anon.ard. Try putting rev=0 in inner for loop.
But you cant get 999999 as the highest palindrome number of 6 digit by your method as u r not checking all the 6 digit numbers.

Answer 2

#include<stdio.h>
int main(void)
{
int rev=0,temp=0,frwd,n,ans=0;
int i,j;
for(i=100000;i<=999999;i++)
{
frwd = n = i;
rev = 0;
while(n!=0)
{
temp = n%10;
n = n/10;
rev = temp+rev*10;
}
if((rev == frwd)&&(ans<frwd))
{
ans=frwd;
}
}
printf("%d\n",ans);
return(0);
}

Answer 3

4 problems with your Code:-
Like another.anon.coward said- you need to put rev=0 inside inner loop
You need to separate each number printed either by a space or a newline ('\n')
printf("\n %d");. Otherwise they will look like one big number (garbage).
Your algorithm is also wrong. According to your program, the largest 6-digit number is 906609 (The correct answer is 999999). For this you should change your inner loop to j=0;j<999;j++ and change n=i*j to n=i*1000+j.
Also move the printf("\n%d",ans); outside the loop.
The corrected program is:
#include <stdio.h>
int main(void)
{
int rev=0,temp=0,frwd,n,ans=0;
int i,j;
for(i=100;i<=999;i++)
{
for(j=0;j<=999;j++) /*CORRECTED THIS LINE,*/
{ rev=0;/*ADDED THIS LINE;*/
n = (i*1000) + j; /*CORRECTED THIS LINE*/
frwd = n;
while(n!=0)
{
temp = n%10;
n = n/10;
rev = temp+rev*10;
}
printf("\n%d",rev); /*THIS LINE,*/
if((rev == frwd)&&(ans<frwd))
{
ans=frwd;
}
}
}
printf("\n%d",ans); /* AND THIS LINE*/
return(0);
}

Answer 4

#include <stdio.h>
int main(void)
{
int rev=0,temp=0,frwd,n,ans=0;
int i,j;
for(i=100;i<=999;i++)
{
for(j=0;j<=999;j++) /*CORRECTED THIS LINE,*/
{ rev=0;/*ADDED THIS LINE;*/
n = (i*1000) + j; /*CORRECTED THIS LINE*/
frwd = n;
while(n!=0)
{
temp = n%10;
n = n/10;
rev = temp+rev*10;
}
printf("\n%d",rev); /*THIS LINE,*/
if((rev == frwd)&&(ans<frwd))
{
ans=frwd;
}
}
}
printf("\n%d",ans); /* AND THIS LINE*/
return(0);
}