Question

I wrote program to convert decimal to binary for practice purposes but i get some strange output. When doing modulo with decimal number, i get correct value but what goes in array is forward slash? I am using char array for being able to just use output with cout <<.

// web binary converter: http://mistupid.com/computers/binaryconv.htm

#include <iostream>
#include <math.h>
#include <malloc.h> // _msize
#include <climits>
#define WRITEL(x) cout << x << endl;
#define WRITE(x) cout << x;

using std::cout;
using std::endl;
using std::cin;

char * decimalToBinary(int decimal);
void decimal_to_binary_char_array();

static char * array_main;

char * decimalToBinary(int decimal) // tied to array_main
{
   WRITEL("Number to convert: " << decimal << "\n");
   char * binary_array;
   int t = decimal,     // for number of digits
       digits = 0,      // number of digits
       bit_count = 0;   // total digit number of binary number
   static unsigned int array_size = 0;
   if(decimal < 0) { t = decimal; t = -t; }  // if number is negative, make it positive
   while(t > 0) { t /= 10; digits++; }       // determine number of digits
   array_size = (digits * sizeof(int) * 3);  // number of bytes to allocate to array_main
   WRITEL("array_size in bytes: " << array_size);
   array_main = new char[array_size];
   int i = 0;  // counter for number of binary digits
   while(decimal > 0)
   {
      array_main[i] = (char) decimal % 2 + '0';
      WRITE("decimal % 2 = " << char (decimal % 2 + '0') << "  ");
      WRITE(array_main[i] << "  ");
      decimal = decimal / 2;
      WRITEL(decimal);
      i++;
   }
   bit_count = i;
   array_size = bit_count * sizeof(int) + 1;
   binary_array = new char[bit_count * sizeof(int)];
   for(int i=0; i<bit_count+1; i++)
      binary_array[i] = array_main[bit_count-1-i];
   //array_main[bit_count * sizeof(int)] = '\0';
   //WRITEL("\nwhole binary_array: "); for(int i=0; i<array_size; i++) WRITE(binary_array[i]); WRITEL("\n");
   delete [] array_main;
   return binary_array;
}

int main(void)
{

   int num1 = 3001; 
           // 3001    = 101110111001
           // 300     = 100101100
           // 1000    = 1111101000
           // 1200    = 10010110000
           // 1000000 = 11110100001001000000
           // 200000  = 110000110101000000
   array_main = decimalToBinary(num1);
   WRITEL("\nMAIN: " << array_main);

   cin.get();
   delete [] array_main;
   return 0;
}

The output:

Number to convert: 3001

array_size in bytes: 48
decimal % 2 = 1  /  1500
decimal % 2 = 0  0  750
decimal % 2 = 0  0  375
decimal % 2 = 1  1  187
decimal % 2 = 1  /  93
decimal % 2 = 1  1  46
decimal % 2 = 0  0  23
decimal % 2 = 1  1  11
decimal % 2 = 1  1  5
decimal % 2 = 1  1  2
decimal % 2 = 0  1  1
decimal % 2 = 1  1  0

MAIN: 1111101/100/

What are those forward slashes in output (1111101/100/)?

Answer 1

It must be array_main[i] = (char) (decimal % 2 + '0'); (note the parentheses). But anyway, the code is horrible, please write it again from scratch.