Program flow is the order in which a computer follows the instructions a programmer gives it.

Normally, a computer will follow the instructions from the first to the last and end the program when there is no more code to run.

; pseudo code 

Display "Hi"
Display "I'm a computer game."
Display "Not really, I'm just an example."
End Game

Printr "Hi."
Printr "I'm a computer game."
Printr "Not really, I'm just an example."

Print "Hi."
Print "I'm a computer game."
Print "Not really, I'm just an example."
WaitKey

10 PRINT "Hi."
20 PRINT "I'm a computer game."
30 PRINT "Not really. I'm just an example."

Print "Hi."
Print "I'm a computer game."
Print "Not really, I'm just an example."
Sleep

Print "Hi."
Print "I'm a computer game."
Print "Not really, I'm just an example."
Sync
WaitKey

In the example above, the computer will run each line in order and end the program after line 3 when there is no more code to run.

Conditional Statements

A conditional statement is a construct which allows code to be executed conditionally depending on the value of an expression.

IF

An If statement checks an expression and runs code depending on the evaluation of an expression. If the expression is true then the code will be run. If it is false, the code will not be executed.

Loops

• Loops

Outdated Program Flow

GOTO

GOTO will skip to a specific line in a program.

1 PRINT "Hi"
2 GOTO 5
3 PRINT "Last line was 6"
4 GOTO 7
5 PRINT "Last line was 2"
6 GOTO 3
7 PRINT "Last line was 4"

This will output :

Hi
Last line was 2
Last line was 6
Last line was 4

LoadFont "Arial", 1, 20, 0

PRINT "Hi"

GOTO Label5
Label3:
    PRINT "Last line was 6"
    GOTO Label7
Label5:
    PRINT "Last line was 2"
GOTO Label3
Label7:
    PRINT "Last line was 4"

Sync
WaitKey

GOSUB

GOSUB will send the program flow to a line where it will continue until it finds RETURN. Then, it will return to just below the original GOSUB.

1 PRINT "About to go on a subroutine."
2 GOSUB 5
3 PRINT "I have returned."
4 END
5 PRINT "I'm on a subroutine."
6 PRINT "I'm about to return."
7 RETURN

This will output :

About to go on a subroutine.
I'm on a subroutine.
I'm about to return.
I have returned.

LoadFont "Arial", 1, 20, 0

Print "About to go on a subroutine."
GoSub Label5

Print "I have returned."
Sync
WaitKey

Label5:
    Print "I'm on a subroutine."
    Print "I'm about to return."
    Return

Subroutines

• Write me

Functions

• Write me

Related Pages

• Function
• Label
• Line Number
• Subroutine

Backlinks

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