Error in program to check whether integer is divisible by 11 or not

Question

3.00/5 (1 vote)

See more:

I Need Help Concerning My C++ Program.
In Need To Write A Program That Checks Whether An Integer Is Divisible By 11 Or Not. Here Is A Copy Of My Code. It Runs Without Errors Though It Gives Wrong result

#include 
#include 
using namespace std;
int n, a, power=0, t=0;
bool divisible (int)
{
	a = abs (n);
	if (a<11)
		return false;
	else if (a=11)
		return true;
	else 
		while ((a/(static_cast<removed int="">(pow(10.0, power)))>=1))
		{
			
			if (((a/(static_cast<removed int="">(pow(10.0, power))))<10))
				switch (power % 2)
			{
				case 0:
				t+=(a/(static_cast<removed int="">(pow(10.0, power))));
				break;
				case 1:
				t-=(a/(static_cast<removed int="">(pow(10.0, power))));
				break;
			}
			
			else 
				switch (power % 2)
			{
				case 0:
				t += ((a/(static_cast<removed int="">(pow(10.0, power))))%10);
				break;
				case 1:
				t-= ((a/(static_cast<removed int="">(pow(10.0, power))))%10);
				break;
			}
			
			power++;
		}
		if (t%11 == 0)
			return true;
		else if (divisible (t) != 0)
			return false;
		
		
}


void main ()
{ 
	cout<<"Enter an integer \n";
	cin>>n;
	switch (divisible (n))
	{
	case 1: cout<<"The number "<<n<<" is divisible by 11 \n";
		break;
	case 0: cout<<"The number "<<n<<" is not divisible by 11 \n";
		break;
	}
}

[Further description of problem posted as reply pasted here]
The question requires us to use the specified formula t = a0 -a1 + a2 - a3...+(-1)kak.. so i would appreciate it if you rather check my posted code .. thanks

The question is:

1. Let n = akak-1ak-2…a1a0 be an integer and t = a0 – a1 + a2 - … + (-1)kak. It is known that n is divisible by 11 if and only if t is divisible by 11. For example, suppose n = 8784204. Then t = 4 – 0 + 2 – 4 + 8 – 7 + 8 = 11. Since 11 is divisible by 11, it follows that 8784204 is divisible by 11. If n = 54063297, then t = 7 – 9 + 2 – 3 + 6 – 0 + 4 – 5 = 2. Because 2 is not divisible by 11, 54063297 is not divisible by 11. Write a function that takes as input an integer and that return a Boolean indicating whether the integer is divisible or not by 11. Write a program to test your function.

Posted 25-Mar-10 4:33am

7mesho

Updated 25-Mar-10 4:58am

HimanshuJoshi

v3

Add a Solution

5 solutions

Solution 4

Thank you very much Luc Pattyn! :-D it worked.. I really appreciate your help

Posted 25-Mar-10 5:29am

7mesho

Solution 2

[Moved the question posted as answer to the original question]

To 7mesho : Please don't add your reply as answer. Modify the question itself

Posted 25-Mar-10 4:44am

7mesho

Updated 25-Mar-10 4:56am

v3

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Luc Pattyn · Accepted Answer · 2010-03-25T05:18:00

"It Gives Wrong result" isn't descriptive nor informative. You could have given examples of cases that work well and others that don't.
You could have said "It almost always returns true".

And you could have found a pattern yourself.

"else if (a=11)..."
Ah the good old operator traps provided by C and C++.

:)

Eugen Podsypalnikov · Accepted Answer · 2010-03-25T05:41:00

A (very) slow solution :-D :

int TakeByIndex(int iTest, int iIndex)
{
  return (iTest % pow(10, iIndex + 1)) / pow(10, iIndex); 
}
 

bool IsDivisibleBy11(int iTest)
{
  int a = 1,
      k = 1,
      i = 0,
      s = 0;
 

  while (k && a) {
    a = TakeByIndex(iTest, i++);
    k = TakeByIndex(iTest, i++);
    s += (a - k);
  }
 

  return (0 == s % 11);
}

Eugen Podsypalnikov · Accepted Answer · 2010-03-25T04:36:00

Solution 1

Try it :) :

bool IsDivisibleBy11(int iTest)
{
  return (0 == iTest % 11);
}

Posted 25-Mar-10 4:36am

Eugen Podsypalnikov

Error in program to check whether integer is divisible by 11 or not

5 solutions

Solution 3

Solution 5

Solution 1

Solution 4

Solution 2

Add your solution here

Preview 0