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Convert a decimal number to binary number

Problem: Given a number, write a program to convert it into binary form.

For example: 
Input: n = 499
Output: 111110011

Input: n = 5
Output: 101

Input: n = 25
Output: 11001
How to convert a decimal to binary?
Binary representation of 25 is (11001)2

Method 1: Recursive
  • if num > 1 
    • push num on stack 
    • do a recursive call on 'num / 2' 
  • pop num from stack, divide it by 2 and print it's remainder
#include<bits/stdc++.h>
using namespace std;

void binary(int n)
{
    if (n > 1)
        binary(n/2);
 
    cout<<n%2;
}

/* driver fucntion */ 
int main(void)
{
    int num = 499;

    binary(num);
    cout<<"\n";    

    return 0;
}
Output: 
111110011
Method 2: iterative 
#include <bits/stdc++.h>
using namespace std;

/* driver fucntion */
int main()
{
    int n = 5;
    string ans = "";

    while(n > 0)
    {
        /* if reminder is 1, append to ans */
        if(n%2!=0)
            ans += "1";
        else
            ans += "0";
        n/=2;
    }

    /* reverse the string to get required answer */
    reverse(ans.begin(), ans.end());

    cout<<ans<<"\n";

    return 0;
}
Output: 
101