Control Flow

Note this page is still in development bug @NonstickAtom785 or @Zeda to get this finished.

Control Flow

If you already know how to use BASIC control flow you can skip to the next section on Grammer's control flow perks. If not, then read up on this section before moving on. There is a lot of info to retain.

Control Flow is the ability to control the flow of your program. We do this by using commands such as If, While, Repeat, For, and Goto/Lbl.

Code Blocks and Loops

Using If-Then-Else

If I use If in a program Then, if the condition is true then the following code will be executed until the corresponding End token is reached.

Code:

If 1
Then
<<<code to execute>>>
End

Note: In Grammer, true simply means non-zero, while 0 is false, as in TI-BASIC.

However, as in TI-BASIC, if we only need to execute one line of code, Then and End can be omitted.

Code:

If 1
<<<code to execute>>>

If I use an If, Then, and Else in a single block then if the condition is true, the following code will be executed until the Else token. If the condition is false the code under Else will be executed until the corresponding End token is reached.

Code:

If 0
Then
<<<code to execute if true>>>
Else
<<<code to execute if false>>>
End

A condition is a line of code to be evaluated. I used 1 and 0 as to represent not just how If sees the equation but all control flow commands. However, you can use a variable such as A or an expression like A>1 which would return 1 if A is greater than 1 and 0 if less than A.

Unlike TI-BASIC, conditions are evaluated up to a newline. This means, for example, that you can include : and → in a condition. For example, you can store 3*N to K, and check if it is less than 100:

If 3*K→N:<100
Then
<<do stuff if 3*K is less than 100>>
Else
<<do stuff if 3*K is not less than 100>>
End

While loops

While is expressed in Grammer just like it is in BASIC. The syntax is While <<<condition>>>. This is a type of loop that executes the code inside of its block while the expression is true. If the expression is not true then the whole block is skipped and the program continues executing after the End.

Code:

.0:Return
While 1
ClrDraw
Text(<sub>o<sub>"Hi there!
DispGraph
End
Stop

This code will continue to clear the graph screen then display the text "Hi there!" forever, unless you break it by pressing [ON].

Instead of using just numbers we can get more control over the flow of the program if we use pvar's and modify them.

Code:

.0:Return
42→L
While L       ;While L is a true statement(not equaling 0) then execute the following code.
If getKey(15
0→L
End
Stop

But that's not all! You can also use commands that return an output.

.0:Return
Pixel-On(0,0
While pixel-Test(0,0    ;Check for pixel
GetInc(B                ;Inc B 
If B=50                 ;If B=50 change the pixel State
Pixel-Change(0,0        ;The pixel logic becomes 0 and the loop ends.
End
Stop

Repeat loops

Repeat is the complete opposite of While . Instead of repeating until the statement becomes false it repeats until the statement become true. This coding block is ideal for checking keys or values to be equal to the desired value or amount.

For loops

Pause If

Labels and Subroutines

Lbl

Return

Goto

▶Nom(

Line Jumping With ln(

prgm

Passing Parameters

Asm(

AsmPrgm

Others

Pause

expr(

Interrupts

Execute a line of code