Thread: need little help in understanding a program code.

The program checks for repeated numbers.

Code:

#include<stdbool.h>
#include<stdio.h>

int main (void)
{

bool digit_seen[10]={false};

int digit ;
long n;

printf("Enter a number:");
scanf("%ld", &n);


while(n>0)

{

digit=n%10;

if ( digit_seen[digit] )
break;

digit_seen[digit] =  true;
n/=10;
}

if (n>10)
printf("Repeated numbers\n");
 else
printf("No Repeated numbers\n");


return 0;

}

here is the part of the code which i m finding little hard to understand--

especially this part.
----------------------------------------------------------------------------
if ( digit_seen[digit] )
break;
----------------------------------------------------------------------------

Code:

while(n>0)

{

digit=n%10;

if ( digit_seen[digit] )
break;

digit_seen[digit] =  true;
n/=10;
}

thanks for helping.

Take for example the entered number is 353.
The array digit_seen[10] is initialized with flase which is 0 hence it is

Code:

digit_seen[10] = {0};

First condtion while(n>0) hence 353 satisfies it enters into the loop.
digit = n % 10 = 353 % 10 = 3 is the remainder.
Next condition
if(digit_seen[digit])
break;
this evaluates to false as digit_seen[3] is false initially.

digit_seen[digit] = true; this evaluates to
digit_seen[3] = 1; ------------(1)
next statement n/=10; this evaluates to n = 353/10 = 35. The while loop continues.

similary for 35,

Next n will be 3.

In this case also while(n >0) satisfies and hence goes into the loop.
here if(digit_seen[digit]) evaluates to digit_seen[3] = 1 from the equation (1) hence this condition satisfies and executes the break statement and comes out of the while loop.
since the value of n is 3 which is less than 10 it prints "No Repeated Numbers". But actually i am finding the repeated numbers. Please verify the logic in the last condition it is if(n > 10).

It appears to be a slightly wonky copy from somewhere like here.

Thanks for the explanation Satya

and yes, you are right, it's a typing mistake.i am sorry regarding it.

i wrote (n>10) instead of (n>0) ...

Code:

if (n>0)

Code:

printf("Repeated numbers\n");
 else
printf("No Repeated numbers\n");


return 0;

}

thats the actually code.

@gemera: the code seems to be exactly same. :P

but i didnt copy it from that website. i m learning c from the book C:A modern approach by k.n king.
and this code is written as an example to understand how arrays works in chapter 8-"ARRAYS" of this book.



THANKS for the help guys