hey guys, I've been trying to work out the formula 'v=I*r'. But whenever I run the program and input values for I and r, it doesn't give the right answer. This is the code #include <iostream> using namespace std; int main() { int i,r; int v = i*r; cout<<"what is the value of i?\n"; cin>>i; cout<<"what is the value of r?\n"; cin>>r; cout<<"voltage ="<<v<<endl; return 0; } p/s: I'm new to programming

Answer 1

When you declare int V, you are setting its value to (I * R), which is fine. Problem is, at this point int I and R have no value.

Set V to (I * R) after you have taken inputs for I and R, just like how Avinash Singh has demonstrated.

Some improvements I can suggest is not using int for those three values. Use a float or even a double. As a scientific equation, a lot of the time you will see decimals in place of I and R (and in turn, V). Additionally, in your example, int V is unnecessary, as you could always do:

cout << "V = " << I * R;

Answer 2

If you want the multiplication of i and r... Then try this..

#include <iostream>
using namespace std;

int main() {
int i,r;
int v;

cout<<"what is the value of i?\n";
cin>>i;
cout<<"what is the value of r?\n";
cin>>r;
v=i*r;
cout<<"voltage ="<<v<<endl;
return 0;
}

Answer 3

at the time of declaring v v is set to I times r. but at that time I and r has no value so declare v at the last

Answer 4

Post your code here so we can help.

Are you using 'int' for I and R by any chance?

Answer 5

wow thanks guys. Really helpful.

Answer 6

in the earlier code snippet, you have initialized v as
v = I*r .
but as of that moment there is no value for i or r (since the cin function, which is used to input and assign data is called later)

now, when the cin statements are executed the values of I and r are assigned to them respectively.

next, when v is called in the cout statement the system assigns a random value (aka garbage value) to v as it does not go back to the assignment statement ie
int v= I*r
thus in a way the relation between v,i and r does not exist.

provide the relation between v,i,r after the cin statements and you're good to go.

hope it helped. :)

Answer 7

thanks Avinash. I made the necessary changes and it worked. can you explain why my first code didn't work?

Answer 8

Well you see.. When you initialized 'v' you made it equal to i*r.
Now at this point value of 'i' and 'r' isnt what you inputed.
It is some garbage value.. Now if multiply now you will get unexpected no.

Once you input i and r. Suppose you put i=3 and r=4.

So now v = i*r; // gives you 12...