First published on MSDN on Oct 08, 2012
Authored by Ed Price
In the
Small Basic FAQ
, it mentions there are 14 keywords:
What are the unique features of the Small Basic language?
-
Size
The Small Basic language consists of just 14 keywords.
==========
Of the 14 keywords, we'll cover 16 of them in this blog post:
And
Else
ElseIf
EndFor
EndIf
EndSub
EndWhile
For
Goto
If
Or
Step
Sub
Then
To
While
==========
Examples...
If, Then, EndIf
If (Clock.Hour < 12) Then
TextWindow.WriteLine("Good Morning World")
EndIf
Else
We can shorten two
if..then..endif
statements to be just one by using a new word,
else
.
If we were to rewrite that program using
else
, this is how it will look:
If (Clock.Hour < 12) Then
TextWindow.WriteLine("Good Morning World")
Else TextWindow.WriteLine("Good Evening World")
EndIf
Goto
If (i < 25) Then
Goto start
EndIf
For, To, EndFor
For..EndFor
is, in programming terms, called a
loop
. It allows you to take a variable, give it an initial and an end value and let the computer increment the variable for you. Every time the computer increments the variable, it runs the statements between
For
and
EndFor
.
This program prints out numbers from 1 to 24 in order:
For i = 1 To 24
TextWindow.WriteLine(i)
EndFor
Step
But if you wanted the variable to be incremented by 2 instead of 1 (like say, you wanted to print out all the odd numbers between 1 and 24), you can use the loop to do that too.
For i = 1 To 24 Step 2
TextWindow.WriteLine(i)
EndFor
While, EndWhile
The While loop is yet another looping method, that is useful especially when the loop count is not known ahead of time. Whereas a For loop runs for a pre-defined number of times, the While loop runs until a given condition is true. In the example below, we’re halving a number until the result is greater than 1.
number = 100
While (number > 1)
TextWindow.WriteLine(number) number = number / 2
EndWhile
Sub, EndSub
A subroutine is a portion of code within a larger program that usually does something very specific, and that can be called from anywhere in the program. Subroutines are identified by a name that follows the
Sub
keyword and are terminated by the
EndSub
keyword. Below is a program that includes the subroutine and calls it from various places.
PrintTime()
TextWindow.Write("Enter your name: ")
name = TextWindow.Read()
TextWindow.Write(name + ", the time now is: ")
PrintTime()
Sub PrintTime
TextWindow.WriteLine(Clock.Time)
EndSub
And, ElseIf
If percentage >= 75 Then
TextWindow.WriteLine("The student’s grade is A.")
ElseIf
percentage < 75
And
percentage >= 60 Then
TextWindow.WriteLine("The student’s grade is B.")
ElseIf
percentage < 60
And
percentage >= 35 Then
TextWindow.WriteLine("The student’s grade is C.")
Else
TextWindow.WriteLine("The student’s grade is D.")
EndIf
Or
Sub subRainyCount
If Rainy = "y"
Or
Rainy = "Y" Then
RainyCount = RainyCount + 1
EndIf
EndSub
Why are there 16 Keywords instead of 14?
Okay, so that was a bit of a joke. Sorry if it was lost on you. Usually when you say/read/hear "Of the X items, we'll cover Y of them..." the Y number is smaller than the X number, not larger.
"And" and "Or" are actually Operators, and they don't count as the Keywords.
So the Keyword list looks like this:
Else
ElseIf
EndFor
EndIf
EndSub
EndWhile
For
Goto
If
Step
Sub
Then
To
While
And the Operator list:
And
Or
If you'd like to write up some short explanations of some of those keywords, I'll add your explanations above the examples. Just leave the suggested text in the comments!
Thanks!
- Tall Basic Ed
