what is the difference between passing by value and passing by reference?

Hey there Jiten,

The main difference is when we pass by reference we are handing in our only copy of the variable, and the function directly modifies that variable, where as when we pass by value we have another variable that points at the other variable, so basically two copies of the same variable, and only the copy is modified leaving our original unchanged.

Think of the GoKart examples that we have worked with previously, and consider this function, I'll try to comment my code. to keep it up, let's say we have two different variables and are writing another charge function.

public int mBarsCount = 8; 
// this is the only variable we have of this function and it is directly modified by our function, this is passing by reference. 

public int drive(int laps) {
mBarsCount -= laps;
return mBarsCount
}

Here is the example of passing by value.

public int mBarsCount = 8; 
public int currentBarCount = mBarsCount; 
// we are assigning two variables in this.

public int drive(int laps) {
currentBarCount -= laps; // in our function we only decrease the copy, never modifying our original variable mBarsCount.
}

In essence, when we are modifying our variable directly we are passing it by reference, when we are creating a copy of our variable and modifying the copy only and keeping the original the same we are passing by value.

Think of passing by value as hand writing an essay. That is your only true copy, you then photo copy 10 sheets of it and let it be passed around, you are now passing your variable the essay, as value.

Thanks I hope this helps, shout at me if it doesn't.