binary to decimal convertor

[hasnainafzal]

#include<iostream>
#include<conio.h>
using namespace std;
void main()
{
int num1,num2,ans,rem;
cout<<"enter the number in decimal:"<<endl;
cin>>num1;
cout<<"number in binary is:"<<endl;
while(num1!=1)
{
rem=num1%2;
num1=num1/2;
cout<<rem;
}
getch();
}

[MiiNiPaa]

What your problem is?

[hasnainafzal]

no problm :D

[MiiNiPaa]

So why do you post ineffective, error-prone, badly formatted code which uses practices everyone advises against?

[hasnainafzal]

its not ur concern whether i upload any program or not...

[AbstractionAnon]

Yes, it is when the program contains errors and bad practices.

This site is frequented by posters just learning C++. To see a program that contains errors and bad practices is misleading to C++ learners.

Problems with your code:
Line 2: conio.h header is deprecated and should not be used.
Line 3: Use of using namespace std; should be avoided.
Line 4: void main () is not valid. main MUST return an int.
Line 6: num2 and ans are not used. Why are they here?
Line 6: variables are poorly named.
Line 10-15: program loops forever if 0 is entered. program doesn't output anything if 1 is entered. Program gives incorrect answer for other values.
Line 15: getch is deprecated

PLEASE USE CODE TAGS (the <> formatting button) when posting code.
It makes it easier to read your code and also easier to respond to your post.
http://www.cplusplus.com/articles/jEywvCM9/

[Yay295]

Here's one that works for all integers.

#include <iostream>
#include <string>


int main ( )
{
	int number, numCopy;

	bool isNegative = false;

	std::string binaryNumber = "";


	do {
		std::cin.sync ( ); std::cin.clear ( ); // clear the error and the input stream

		std::cout << "Please enter an integer: "; // ask for a number

		std::cin >> number; // get a number

		if ( !std::cin ) std::cout << "\nThat number could not be read. Please try again.\n\n";
	} while ( !std::cin );


	if ( number < 0 )
	{
		isNegative = true;

		number -= number * 2; // make number positive
	}


	if ( number ) // if number is not 0
	{
		numCopy = number; // make a copy of the original number


		while ( numCopy ) // and get its value in binary
		{
			if ( numCopy & 1 ) binaryNumber = '1' + binaryNumber;

			else binaryNumber = '0' + binaryNumber;

			numCopy = numCopy >> 1;
		}
	}

	else binaryNumber = "0";


	if ( isNegative ) // if the number is negative, take the two's complement
	{
		size_t strLength = binaryNumber.length ( );

		for ( size_t i = 0; i < strLength; ++i ) // get inverse
		{
			if ( binaryNumber[i] == '0' ) binaryNumber[i] = '1';

			else binaryNumber[i] = '0';
		}

		for ( size_t i = strLength - 1; i >= 0; --i ) // and add one
		{
			if ( binaryNumber[i] == '0' )
			{
				binaryNumber[i] = '1';
				break;
			}

			else binaryNumber[i] = '0';
		}

		if ( binaryNumber[0] == '0' ) binaryNumber.erase ( 0, 1 ); // if the first char is 0, erase it
	}


	std::cout << '\n' << number << " is represented in binary as " << binaryNumber << "\n\n";
}

Edit: I made it work for negative integers.