Decimal to Binary Conversion program

acidbeat311 · 01-12-2006, 05:53 PM

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?

Rashakil Fol · 01-12-2006, 06:06 PM

You incremented count after inserting your last binary digit into binary_backwards.

quzah · 01-12-2006, 06:19 PM

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.

peterchen · 01-12-2006, 08:38 PM

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.

logicwonder · 01-12-2006, 09:48 PM

You can do this in more simpler!

**Dave_Sinkula** · 01-12-2006, 10:26 PM

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
*/

01-12-2006, 05:53 PM	#1
acidbeat311 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.
acidbeat311 is offline

01-12-2006, 06:06 PM	#2
Rashakil Fol aoeuhtns Join Date: Jul 2005 Posts: 581	You incremented count after inserting your last binary digit into binary_backwards.
Rashakil Fol is offline

01-12-2006, 06:19 PM	#3
quzah +++ OK NO CARRIER Join Date: Oct 2001 Posts: 10,640	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. __________________ Hundreds of thousands of dipshits can't be wrong. Are you up for the suck?
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01-12-2006, 08:38 PM	#4
peterchen 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.
peterchen is offline

01-12-2006, 09:48 PM	#5
logicwonder Logic Programmer Join Date: Nov 2005 Location: Kerala, India Posts: 52	You can do this in more simpler! __________________ L GIK wins!!! Salutes from logicwonder Enjoy programming
logicwonder is offline

01-12-2006, 10:26 PM	#6
Dave_Sinkula Just Lurking Join Date: Oct 2002 Posts: 5,005	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.
Dave_Sinkula is offline

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