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Mar 3rd, 2009

Decimal to Binary Conversation stored into a char array

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Hello, I am trying to create a program where I can work with an array of char that contain either 0 or 1 representing a decimal number that the user enters.

Basically I need to convert a decimal number into binary and store it into a char array. I wrote this program but it is outputting something weird.

c++ Syntax (Toggle Plain Text)
char binary(int number)
{
	int temp = 0, c = 0;
	char buffer;
 
	if (number % 2 == 0)
	{
		temp = number / 2;
	}
	else
	{
		number = number - 1;
		temp = number / 2;
	}
 
	if (temp % 2 == 0)
	{	
		buffer = '0';
	}
	else
	{
		buffer = '1';
	}
 
	return buffer;
}
 
int main()
{
	int num;
 
	cin >> num;
 
	while(num != 0)
	{
		cout << binary(num);
 
		if (num % 2 == 0)
		{
			num = num / 2;
		}
		else
		{
			num = num - 1;
			num = num / 2;
		}
	}
 
	return 0;
}
 
Can someone help me out??
char binary(int number)
{
	int temp = 0, c = 0;
	char buffer;

	if (number % 2 == 0)
	{
		temp = number / 2;
	}
	else
	{
		number = number - 1;
		temp = number / 2;
	}
	
	if (temp % 2 == 0)
	{	
		buffer = '0';
	}
	else
	{
		buffer = '1';
	}

	return buffer;
}

int main()
{
	int num;

	cin >> num;

	while(num != 0)
	{
		cout << binary(num);
		
		if (num % 2 == 0)
		{
			num = num / 2;
		}
		else
		{
			num = num - 1;
			num = num / 2;
		}
	}

	return 0;
}

Can someone help me out??

djextreme5

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Mar 3rd, 2009

Re: Decimal to Binary Conversation stored into a char array

try something along the lines of itoa which should allow you to use base 2 to convert it to binary

it would look like so: itoa(temp, chararray, 2)

rgfirefly24

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Mar 3rd, 2009

Re: Decimal to Binary Conversation stored into a char array

I cannot use itoa();

I already did that and it won't compile on my teacher's computer. Apparently she is using some website's judging process and it has a g++ compiler. Since itoa() is not a standard function, g++ doesn't support it.

djextreme5

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Mar 3rd, 2009

Re: Decimal to Binary Conversation stored into a char array

uhmmm... Why don't you just loop through all the bits in the value shifting it over, then checking it with a logic AND(mask 1). Add "1" to it if it's true, else "0".
Simple?

MosaicFuneral

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Mar 3rd, 2009

Re: Decimal to Binary Conversation stored into a char array

Click to Expand / Collapse Quote originally posted by MosaicFuneral ...

uhmmm... Why don't you just loop through all the bits in the value shifting it over, then checking it with a logic AND(mask 1). Add "1" to it if it's true, else "0".
Simple?

What do you mean?

djextreme5

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Mar 3rd, 2009

Re: Decimal to Binary Conversation stored into a char array

Lets say you have the value ten, and in binary that is represented as "00001010." Mask(AND operator) all the bits before the first one and the truth is now false, place a zero to the array; shift the original value right once and mask again, this time the truth is true, add an "1"; repeat.

Well the array would look like "01010000" if you did that, there's an easy fix or just reverse it. If that's to much for you, can you use C++'s bitset class container?

Last edited by MosaicFuneral; Mar 3rd, 2009 at 10:06 pm.

MosaicFuneral

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Re: Decimal to Binary Conversation stored into a char array

just write your own itoa.

c++ Syntax (Toggle Plain Text)
#include <iostream>
#include <string>
 
using namespace std;
 
string itoa(const int &integer,int base=10)
{
    if (integer==0) return string("0");
 
    string a;
    int start, digits, piece;
 
    //count digits
    digits=0;
    piece=((integer<0)? 0-integer : integer);
    while( piece > 0 )
    {
        piece-= (piece%base);
        piece/=base;
        digits++;
    }
 
    start=((integer<0)? 1 : 0);
    a.resize(digits+start,' ');//allocate memory only once
    if (integer<0) a[0]='-';
 
    piece=((integer<0)? 0-integer : integer);
    for(int i=0;  piece > 0; i++ )
    {
        a[ digits+start-i-1] = (piece%base)+48;
        piece-= (piece%base);
        piece/=base;
    }
 
    return a;
}
 
 
int main(int argc, char*argv[])
{
    cout << itoa(55) << endl; //defaults to base 10
    cout << itoa(0,2) << endl;// 0
    cout << itoa(1,2) << endl;// 1
    cout << itoa(2,2) << endl;// 10
    cout << itoa(3,2) << endl;// 11
    cout << itoa(4,2) << endl;// 100
    cout << itoa(5,2) << endl;// 101
    cout << itoa(63,2) << endl;// 111111
    cout << itoa(-1,2) << endl;// -1
    cout << itoa(-2,2) << endl;// -10
}
#include <iostream>
#include <string>

using namespace std;

string itoa(const int &integer,int base=10)
{
    if (integer==0) return string("0");

    string a;
    int start, digits, piece;

    //count digits
    digits=0;
    piece=((integer<0)? 0-integer : integer);
    while( piece > 0 )
    {
        piece-= (piece%base);
        piece/=base;
        digits++;
    }

    start=((integer<0)? 1 : 0);
    a.resize(digits+start,' ');//allocate memory only once
    if (integer<0) a[0]='-';

    piece=((integer<0)? 0-integer : integer);
    for(int i=0;  piece > 0; i++ )
    {
        a[ digits+start-i-1] = (piece%base)+48;
        piece-= (piece%base);
        piece/=base;
    }

    return a;
}


int main(int argc, char*argv[])
{
    cout << itoa(55) << endl; //defaults to base 10
    cout << itoa(0,2) << endl;// 0
    cout << itoa(1,2) << endl;// 1
    cout << itoa(2,2) << endl;// 10
    cout << itoa(3,2) << endl;// 11
    cout << itoa(4,2) << endl;// 100
    cout << itoa(5,2) << endl;// 101
    cout << itoa(63,2) << endl;// 111111
    cout << itoa(-1,2) << endl;// -1
    cout << itoa(-2,2) << endl;// -10
}

Last edited by blacklight332; Mar 3rd, 2009 at 10:46 pm.

blacklight332

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