Thread: 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?

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.

You can do this in more simpler!

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
*/