Decimal Number using for loop in C++

The Binary Value of Decimal Number using for loop

#include

#include

int main()

{

  int n,x,a, c, k;

  cout<<"enter an integer in decimal number system";

  cin>>x;

  n=x;

  cout<<"binary value of given number is: ";

  for( a=1;n!=0;a++)

 {

     n=n/2;

       }

          a=a-2;

  for (c = a; c >= 0; c--)

  {

    k = x >> c;

    if (k & 1)

   cout<<"1";

else

      cout<<"0";

  }

            return 0;

}

The area of any triangle using heron's formula

#include
#include

#include
 int main()

{

    float first,second,third;

    float s,area;

    cout<<"enter size of each sides of triangle"<
    cout<<"enter size for first side =";

    cin>>first;

    cout<<"enter size for second side =";

    cin>>second;

    cout<<"enter size for third side =";

    cin>>third;

    s = (first+second+third)/2;

    area = sqrt(s*(s-first)*(s-second)*(s-third));

    cout<<"area of triangle= "<    

 return 0;
}

Swap two variables without using third variable

#include
#include

int main()

{
int var1, var2;
 cout<<"enter value for first integer:  ";
 cin>>var1;
 cout<<"enter value for second integer:  ";
 cin>>var2;
 cout<<" values before swapping:  "<  cout<<"first integer ="<  cout<<"second interger ="<
              var1=var1+var2;
              var2=var1-var2;
              var1=var1-var2;
 cout<<" values after swapping:  "<  cout<<"first integer ="<  cout<<"second interger ="<

return 0;

}