what's the problem here??

Question

When I run this:
#include<iostream>
using namespace std;
int main()
{
float a=10000, b=10000*0.28, c=10000*0.27, d=3600+b;
cout<<"JANUARY 21-->"<<"\t";
cout<<"Basic :"<<a<<"\t";
cout<<"DA :"<<b<<"\t";
cout<<"HRA :"<<c<<"\t";
cout<<"Convance :"<<d<<"\t";
cout<<"Total :"<<a+b+c+d;
return 0;
}

I got answer as :
JANUARY 21--> Basic :10000 DA :2800 HRA :2700 Convance :6400
Total :121900

But when I run this I got answer as :

#include<iostream>
using namespace std;
int main()
{
float a, b=a*0.28, c=a*0.27, d=3600+b;
cout<<"Enter the amount :";
cin>>a;
cout<<"JANUARY 21-->"<<"\t";
cout<<"Basic :"<<a<<"\t";
cout<<"DA :"<<b<<"\t";
cout<<"HRA :"<<c<<"\t";
cout<<"Convance :"<<d<<"\t";
cout<<"Total :"<<a+b+c+d;
return 0;
}
This is the I have got :
Enter the amount :10000 JANUARY 21--> Basic :10000 DA :0 HRA :0
Convance :3600 Total :13600

I don't know why I got different answers. Any one pls explain it.

Answer 1

Bro. Try like this :

#include<iostream>
using namespace std;
int main()
{
float a;
cout<<"Enter the amount :";
cin>>a;
float b=a*0.28, c=a*0.27, d=3600+b;
cout<<"JANUARY 21-->"<<"\t";
cout<<"Basic :"<<a<<"\t";
cout<<"DA :"<<b<<"\t";
cout<<"HRA :"<<c<<"\t";
cout<<"Convance :"<<d<<"\t";
cout<<"Total :"<<a+b+c+d;
return 0;
}

Answer 2

You need to initialize variable a before you initialize variables b, c, d, because by default they are equal 0