In the Microsoft Small Basic programming language, there are five types of control statements - If statement, Goto statement, While loop statement, For loop statement, and subroutine call statement.  These statements build-up with only fourteen keywords of Small Basic.  This article is an overview of these control statements.  Control statements change program flow respectively.

If statement

If the statement or If clause is for making a conditional branch.  If you'd like to show "AM" or "PM" by checking the clock, following code and chart are for that.  There is another keyword "ElseIf" for this clause.  For detail about "ElseIf", see the next section.

' Start
hour = Clock.Hour             ' Get hour
If hour < 12 Then             ' hour < 12?
  TextWindow.WriteLine("AM")  ' Yes: Write "AM"
  TextWindow.WriteLine("PM")  ' No: Write "PM"
' End

Goto statement

Goto statement can jump anywhere labeled place in the program.  The label is written with colon such as "start:".  Following sample, the program checks input text, and if it is "Y" or "N" then shows "True" or "False", otherwise input text again with Goto statement inline 10.

1.' Start
3.TextWindow.Write("1+1=2 Y/N? ") ' Write "1+1=2 Y/N? "
4.ans TextWindow.Read()         ' Read ans
5.If ans = "Y" Then               ' ans?
6.  TextWindow.WriteLine("True")  ' "Y": Write "True"
7.ElseIf ans = "N" Then
8.  TextWindow.WriteLine("False") ' "N": Write "False"
10.  Goto start                    ' other: input again
12.' End

While loop statement

While loop statement repeats statements while condition is true.  In following case, while condition "i <= 10" is true, "n = n + 1" and "i = i + 2" are repeated. 

' Start
n = 0
i = 2
While i <= 10
  n = n + i
  i = i + 2
TextWindow.WriteLine(n)    ' Write n
' End

For loop statement

For loop, statement repeats statements with increasing or decreasing a variable.  In following case, statement "n = n + i" is repeated with increasing a variable "i" from 2 to 10 by inclement 2.  And this sample shows the same result with the sample above.

' Start
n = 0
For i = 2 To 10 Step 2
  n = n + i
TextWindow.WriteLine(n) ' Write n
' End

Subroutine call statement

Subroutine call statement calls subroutine as follows. 

' Start
A()                              ' Call A
' End
Sub A
  TextWindow.WriteLine("A")      ' Write "A"
EndSub                           ' Return

See Also

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