Decimal to Binary Conversion program

This is a discussion on Decimal to Binary Conversion program within the C Programming forums, part of the General Programming Boards category; Hello, I wrote this program for my Intro to Digital Systems class to convert a base 10 number into a ...

  1. #1
    Registered User
    Join Date
    Feb 2005
    Posts
    21

    Decimal to Binary Conversion program

    Hello, I wrote this program for my Intro to Digital Systems class to convert a base 10 number into a Binary base 2 number string. It works perfectly except for some numbers it slams a number in front of it. On linux this number is -1073742772. Such a number is 60.
    Code:
    #include <stdio.h>
    
    
    int main()
    {
    	int input=0;
    	int count=0;
    	int binary_backwards[32];
    	int binary_string[32];
    	int i=0;
    	int j=0;
    	printf("Enter a base 10 positive number to convert to binary:");
    	scanf("%i", &input);
    
    	while(input >0 && count<32)
    	{	
    		binary_backwards[count] = input %2;
    		input /=2;
    		count++;
    	}
    
    	while(count >-1)
    	{
    		binary_string[i]=binary_backwards[count];
    		count--;
    		i++;
    	}
    	
    	while(j<i)
    	{
    		printf("%i", binary_string[j]);
    		j++;
    	}
    	return 0;
    }
    Anyone have any ideas why this is happening?
    Last edited by acidbeat311; 01-12-2006 at 05:56 PM.

  2. #2
    aoeuhtns
    Join Date
    Jul 2005
    Posts
    581
    You incremented count after inserting your last binary digit into binary_backwards.

  3. #3
    ATH0 quzah's Avatar
    Join Date
    Oct 2001
    Posts
    14,826
    You should also consider not using fixed numbers (32), and instead consider using provided limits instead:
    Code:
    #include<limits.h>
    ...
    for( x = 0; x < sizeof( int ) * CHAR_BIT; x++ )
        ...
    This will ensure that it works correctly for say, old crappy DOS compilers that most people around here seem to use.


    Quzah.
    Hope is the first step on the road to disappointment.

  4. #4
    Registered User
    Join Date
    Dec 2005
    Location
    Australia - Melbourne
    Posts
    63
    here is what i would do to fix it

    replace the code below which is in your program
    Code:
    while(count >-1) {
        binary_string[i]=binary_backwards[count];
        count--;
        i++;
    }
    
    while(j<i) {
        printf("%i", binary_string[j]);
        j++;
    }
    with this

    Code:
    while ((--count) > -1) 
        printf("%d", binary_backwards[count]) ;
    hence you can also get rid of
    Code:
    int binary_string[32];
    int i=0;
    int j=0;
    i'm new to c aswell hope i've been a help.

  5. #5
    Logic Programmer logicwonder's Avatar
    Join Date
    Nov 2005
    Location
    Kerala, India
    Posts
    52
    You can do this in more simpler!
    L GIK wins!!!
    Salutes from logicwonder
    Enjoy programming

  6. #6
    Just Lurking Dave_Sinkula's Avatar
    Join Date
    Oct 2002
    Posts
    5,006
    A different tack:
    Code:
    #include <stdio.h>
    
    void dectobin(int value)
    {
       if ( value )
       {
          dectobin(value / 2);
          printf("%d", value % 2);
       }
    }
    
    int main(void)
    {
       dectobin(12345);
       putchar('\n');
       dectobin(60);
       putchar('\n');
       return 0;
    }
    
    /* my output
    11000000111001
    111100
    */
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

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