Thread: Converting Decimal to Binary Numbers using Recursion

  1. #1
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    Oct 2005
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    Converting Decimal to Binary Numbers using Recursion

    I am trying to make a program that will convert a decimal number to its binary equivilant. It will output the first number but I am having trouble figuring out how to use the previously found quotient to find a new quotient. I tried using loops to do this and they are always infinite.

    Here is the code I have written so far

    Code:
    #include <iostream>
    using namespace std;
    
    void convert (int);
    
    int main ()
    
    {
    	int num;
    
    	cout <<"Please enter a number to convert" <<endl;
    	cin>>num;
    
    	convert (num);
             return 0;
    
    }
    
    void convert (int num)
    
    {
    
    	if (num>0)
    	{
    		double quotient,remainder;
    		
    		quotient=num/2;
    		remainder=num%2;
    	
    		if (quotient==0)
    			cout <<" ";
    		else 
    		{
    
    		    if (remainder==0)
    				cout<<"0";
    			else if (remainder==1)
    				cout<<"1";
    			
    		}
    }
    
    	else
    		cout<< " ";
    
    }

  2. #2
    Moderately Rabid Decrypt's Avatar
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    Milwaukee, WI, USA
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    If I understand what you want to do correctly, loops will be the way to go. What loops have you tried? It was most likely a problem with the way you implemented the loop that was causing a problem, as opposed to the idea of using loops messing things up.
    There is a difference between tedious and difficult.

  3. #3
    Registered User
    Join Date
    Feb 2003
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    596
    Jaisch. you're on the right track, but:
    1: you forgot the recursion; i.e. you didn't deal with the whole situation when quotient != 0
    2: You still have more to do when quotient == 0
    3: Your algorithm is going to find 2^0, then 2^1, then 2^2, etc., which is fine but you're going to end up printing the binary number in reverse unless you do something to handle that.
    4: Why output anything when num == 0? Just return.
    Last edited by R.Stiltskin; 10-24-2005 at 10:38 PM.

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