Wrong output using int for finding simple interest

[XProtocol]

I made a simple program to find out simple interest. But when I use int(integer) for variable deceleration it shows wrong output. Whereas using double and float it is showing correct.

void main()
{
 clrscr();
 int i,p,r,t;
 cout<<"Enter Principal ";
 cin>>p;
 cout<<"Enter Interest rate ";
 cin>>r;
 cout<<"Enter time ";
 cin>>t;
 i=p*r*t/100;
 cout<<"Interest= "<<i;
 getch();
}

NOTE: I code in TurboC++ which need clrscr(); and getch(); to get correct output. So, I'm sure they are not causing any problems.

[shadowmouse]

That's because dividing an int by an int will alway produce an int as an output unless you cast it to a float. I would suggestcout<<"Interest= "<<(float)(p*r*t/100);. Or just declare i as a float. You don't actually specify as to why you need to use ints, is there a reason?

[XProtocol]

No its my habit to use ints for programs like this.
Anyway you said "dividing an int by an int will always produce an int" but when I take
principal = 3000
interest rate = 5
time = 4
It gives output -55. How's it possible??

And when I use float instead of int it gives 600, which is correct. Also note that 600 is also an integer.

[AbstractionAnon]

No its my habit to use ints for programs like this.

Well, that's wrong in this instance.

If t is 4, what do you think t/100 (line 11) produces?
Hint: 0. p*r*0 will always be 0.
Not sure where you're getting the -55.

[cire]

If t is 4, what do you think t/100 (line 11) produces?

Multiplication and division have the same precedence level and both associate left-to-right. So, all the multiplication on that line is done before the division.

Not sure where you're getting the -55.

I am. He's in an environment where the native size of int is 16 bit and he's running into overflow. 3000 * 5 * 4 is a greater value than a 16 bit signed int can hold.

http://ideone.com/7L40Kn

If at all possible, I would recommend the OP upgrade to a modern C++ compiler.

[XProtocol]

Alright, thanks helping. :)