Flow control is one of the most important parts of programming. It allows programs to perform operations that are not defined to give the same output each time and to vary based on input.
In a simple definition, flow control is like a road with many roads branching off of it - go left and you end up in town A or go right and you end up in town B. In this situation, a decision is made. The decision is based on some condition; you are going there because there is something you need there and it has it. This is where conditions come in.
In VB.NET there are many ways of controlling the flow, but the most obvious is the if statement. This specific article will focus on variables which have been assigned to the value of an evaluated condition.
Conditions
A condition is a set of requirements. When a condition is met, it is said to be satisfied.
Conditions have special operators, as mentioned in the section of this tutorial on
operators. The And
and Or
keywords are the two main operators in VB.NET. There is also a Not
logical operator in VB.NET.
The following is an example of three types of conditions in VB.NET:
Dim v1 As Boolean = True = False Or True Console.WriteLine(v1) Dim v2 As Boolean = True And False Console.WriteLine(v2) Dim v3 As Boolean = Not(True) Console.WriteLine(v3)
Conditions can be used not just to check for equality, but also to access mathematical comparisons:
Dim x As Boolean x = 20 > 10 Console.WriteLine(x) x = 20 < 10 Console.WriteLine(x) x = 20 >= 20 Console.WriteLine(x) x = 20 <= 10 Console.WriteLine(x)