CODEWITHSUNDEEP
c#arrays
Patrick Boston
Patrick Boston

Reputation: 77

Array Questions

Recently had a quiz in my C# class and got some things wrong. I think I have the answers but I want to make sure I am right.

First one:

Explain the result

int[] myArray = {5,10,15,20,25};
DoWork(myArray);

void DoWork(int[] theArray)
{
    for (int c = 0; c < theArray.Length; c++)
    {
        theArray[c] = 1;
    }
    theArray = null;
}

For this one, I only got half of it right. I said that the loop would set the value for each element in the array to 1. So my question is, what happens when you set the array to null?

Second one:

Explain the result

int[] myArray = {5,10,15,20,25};
DoWork(myArray[1]);

void DoWork(int theItem)
{
    theItem = -1;
}

This one I got completely wrong. The correction was that myArray[1] = 10 still. Is this because it is not being passed by reference? This just confused me a lot because I ran a little test program on the first one (without the null part) and all the values were set to 1 in the array but I was not passing by reference.

Upvotes: 0

Views: 137

Answers (1)

paulsm4
paulsm4

Reputation: 121869

Q: what happens when you set the array to null?

A: "theArray" (inside the routine) is set to null. But "myArray" (outside of the routine) is UNCHANGED. The reason is that "myArray" is an object reference, which is passed by value into DoWork().

Q: Is this because it is not being passed by reference?

A: Yes, exactly. From the link above:

https://msdn.microsoft.com/en-us/library/9t0za5es.aspx

Any changes to the parameter that take place inside the method have no affect on the original data stored in the argument variable.

These links explain further:

Upvotes: 4

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