Chapter 3 Major VB.NET Changes(3)

In VB6, you could call this sub in one of two ways:
foo “Hello ”
Call foo(“Hello ”)
In VB.NET, you also could call this sub in one of two ways:
Foo(“Hello ”)
Call foo(“Hello ”)
The difference, of course, is that the parentheses are always required in the VB.NET
calls, even though you aren’t returning anything. The Call statement is still sup-ported,
but it is not really necessary.
Changes to Boolean Operators
The And , Not , and Or operators were to have undergone some changes. Microsoft
originally said that the operators would short-circuit, but now they are staying the
way they worked in VB6. This means that in VB.NET, as in VB6, if you had two
parts of an And statement and the first failed, VB6 still examined the second part.
Examine the following code:
Dim x As Integer
Dim y As Integer
x =1
y =0
If x =2 And y =5/y Then
As a human, you know that the variable x is equal to 1 . Therefore, when you look at
the first part of the If statement, you know that x is not equal to 2 , so you would log-ically
think it should quit evaluating the expression. However, VB.NET examines the
second part of the expression, so this code would cause a divide-by-zero error.
If you want short-circuiting, VB.NET has introduced a couple of new operators:
AndAlso and OrElse . In this case, the following code would not generate an error in
Dim x As Integer
Dim y As Integer
x =1
y =0
If x =2 AndAlso y =5/y Then
This code does not cause an error; instead, because x is not equal to 2 , VB.NET does
not even examine the second condition.


E-Commerce Solutions

Leverage the same tools powering the Alibaba Ecosystem

Learn more >

Apsara Conference 2019

The Rise of Data Intelligence, September 25th - 27th, Hangzhou, China

Learn more >

Alibaba Cloud Free Trial

Learn and experience the power of Alibaba Cloud with a free trial worth $300-1200 USD

Learn more >



如果您發現本社區中有涉嫌抄襲的內容,歡迎發送郵件至: 進行舉報並提供相關證據,工作人員會在 5 個工作天內聯絡您,一經查實,本站將立刻刪除涉嫌侵權內容。