What am I doing wrong with this array?

[Whiplash17]

So in this method im trying to make a decimal to binary method that I can use later. when ever I enter a number for a I get some weird stuff for an output. like if I entered 6 for a, I get 2686808-192466809244744141985802686...."blah blah blah"....77024110

#include <iostream>


using namespace std;
void binary(int n)
{
    int binaryArray [8];
    int tempBinary;
    for(int i = 0; n != 0; i++)
    {
        tempBinary = n%2;
        binaryArray[i] = tempBinary;
        n = n/2;
    }
    for(int i = sizeof(binaryArray)-1; i >= 0; i--){
        cout << binaryArray[i];
    }


}

int main(int nNumberofArgs, char* pszArgs[])
{
    cout << "Please enter a value for 'A' and a value for 'B'";
    int a;
    int b;
    int n;
    cin >> a >> b;
    n = a;
    binary(n);
}

Any ideas?

[Jikax]

Could you please use code tags?

And you got errors because you don't initialize the array completely. It is printing rubbish, I guess you entered 6 right? Look t the last 3 numbers, 110 is binary 6.

Why not use bit shifting:

for(int i=0;i<8;i++)
{
  binaryArray[i] = n & 0x01;
  n = n >> 1;
}

for(int i=7;i>=0;i++)
{
  cout << binaryArray[i];
}

[mik2718]

The last 3 numbers are 110 which is binary for 6 - so it works!

Now you need to avoid outputting the other stuff, maybe if you just initialize the array to all 0 first the output will make more sense.

[Whiplash17]

I went ahead and initialized all to zero. I still get all the jibberish in front but it now ends with 00000110.

[cire]

#include <iostream>


using namespace std;
void binary(int n)
{
	int binaryArray [8];
	int tempBinary;
	for(int i = 0; n != 0; i++)
	{
		tempBinary = n%2;
		binaryArray[i] = tempBinary;
		n = n/2;
	}
	for(int i = sizeof(binaryArray)-1; i >= 0; i--){
		cout << binaryArray[i];
	}


}

int main(int nNumberofArgs, char* pszArgs[])
{
	cout << "Please enter a value for 'A' and a value for 'B'";
	int a;
	int b;
	int n;
	cin >> a >> b;
	n = a;
	binary(n);
}

Look at line 15.

sizeof(binaryArray) is much larger than the number of elements in the array.

sizeof(binaryArray)/sizeof(binaryArray[0]) is correct.

Also if you make line 7:

int binaryArray [sizeof(int)*8] = {0};

There will be enough storage no matter what the value passed in is (making the assumption that bytes are 8 bits -- they aren't on all platforms) and all of the elements will be initialized to 0.

[Jikax]

It is because you use sizeof... Sizeof gets the size of the array in bytes and your array is made of ints which are more than 1 byte each so it will result in a larger number than the 8 you expect... 8*sizeof(int)

[Whiplash17]

Huzzah! Many thanks guys/gals!

[Perman]

Use itoa();

/* itoa example */
#include <stdio.h>
#include <stdlib.h>

int main ()
{
  int i;
  char buffer [33];
  printf ("Enter a number: ");
  scanf ("%d",&i);
  itoa (i,buffer,10);
  printf ("decimal: %s\n",buffer);
  itoa (i,buffer,16);
  printf ("hexadecimal: %s\n",buffer);
  itoa (i,buffer,2);
  printf ("binary: %s\n",buffer);
  return 0;
}

[Perman]

Since itoa() function is NOT an ANCI C++ function, here id another way to do it that I have been using in several micrcontrollers.

#include <stdio.h>
#include<conio.h>

int main()

{
    printf("Binary value of 1234 is: %s\r\n", itob(1234); 
    getch();
}

// Integer to binary ascii string
char *itob(uint uiInt)
{
char szStr[33];
uint  uiTemp;
uchar ucPtr     = 0;
uchar ucStart   = 0;
uint  uiDivider = 0x8000;

// Because integer can be (32bit) or (16bit) then test for it.
// Compiler depended.
    if (sizeof(uiInt) > 2) {
        uiDivider = 0x80000000;
    }

   // Do all bits and start making string on first '1' binary
    do {
        uiTemp = (uiInt / uiDivider);
        if (uiTemp == 1) {
            uiInt -= uiDivider;
           // Set flag for first '1' to do string
            ucStart = 1;
        }
        uiDivider /= 2;
       // Make ascii
        szStr[ucPtr] = (char)(uiTemp + '0');
       // If result have been a '1' then increment pointer
        if (ucStart == 1) {
            ucPtr++;
        }
   // Repeat until last bit
    } while (uiDivider >= 2);

   // Make ascii
    szStr[ucPtr++] = (char)(uiInt + '0');
   // End string with NULL
    szStr[ucPtr] = 0;

    return szStr;
}