What do byval and byref mean and which is the default

Macro Settings Code Modules Region and Language Windows API So Number1 started out having a value of After our Sub got called, we added 1 to Number1. So we should have 11 in the message box, right? The reason Number1 didn't get incremented was because we specified ByVal in the Sub:. This means that only a copy of the original variable got passed over.

When we incremented the variable, only the copy got 1 added to it. The original stayed the same - This time, you should see 11 displayed in the message box.

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Difference between ByVal and ByRef? Ask Question. Asked 10 years, 9 months ago. Active 2 months ago. Viewed 37k times. Voldemort Voldemort Martinho Fernandes. Preface: I am not a VB programmer. If you know you're not going to modify it, ByRef could be faster and the function would behave the same. I commented the same thing below, but just in case ByVal does not create a copy of the object with the exception of value type variables.

It creates a new reference to the same object. You are right that ByRef may be faster doesn't have to create a new reference but the difference would be insignificant at best.

Add a comment. Active Oldest Votes. As simple as I can make it. One simple way to tell is how you assign the variable for that type. For example, look how we assign the Integer variable and the Range variable:.

There are subtle differences between using value types and reference types when passing data to a procedure using ByVal and ByRef. The table below describes the basics of what happens in each scenario. You can copy a piece of paper and hand it to someone. We then change the data in the variable s and print its value again, which now shows new message. However, when we get back to the ByValueExampleWithValueType procedure, we print the str variable, which is still set to hello.

Passing a value type using ByVal lets us hand out a copy of the data, rather than give access to the original data itself. This is a good thing, since we may not want other procedures to be able to change variables in our main procedure. A reference is an address to the variable in memory on your computer. Think of it like a home address. You can give someone a home address and they can figure out how to get there. Once they get there, they can change things like mowing your lawn or painting your house.

In this example, we set the cell variable to the A1 range on the current worksheet. We then change the value to hello. Then we pass the cell variable to the ChangeCell procedure using ByVal. Since cell is a reference type, what we really passed to ChangeCell is a copy of the reference to that same cell. Then we update the value of the cell to new message.