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DVD-lab

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LabTALK is an interpreter language based on the BASIC language. The task of this document is not to teach BASIC, but rather to point out the similarities and differences between it and LabTALK. Therefore the documents below assume that you have some general programming knowledge.

Variables

LabTALK can work with integer, float and string variables. There is no forward declaration of variables like in advanced languages (C, or Pascal..) The variable becomes the type as soon as you assign a value to it for first time.

a = 10

will create integer variable 'a'

b = 10.5

will create float variable 'b'

name = "Hello!"

will create string variable 'name'. If you need to enter '\' you need to do it like in the C language with double '\\'

file = "c:\\myfile.txt"

You can create your very first program quite easily:

string = "Hello!" print string


Then hit the Run button and watch the output tab:


Arrays

Arrays don't have to be declared as to type or number of elements. They all could be integer, float or string.

myarray[0] = 10 myarray[1] = 20

Arrays in LabTALK can go even to negative:

myarray[-1] = 10


is still valid. In fact you can mix various types within one array - but of course this is not advised and is of little benefit.


The array index may be a constant, another variable or an expression. See the code below:

a = 5 myarray[a] = 10 myarray[a+1] = 20 print myarray[6]

The printed result is of course 20.

Expressions

LabTALK has fully developed integer and float expressions.

b = 3 a = 3 + 2 * 5 + 4*(10+b*(23+b)) print a


The result is 365. You can use expressions directly in any function.

String operations

LabTALK can use various string operations as well. See the code below:

c = "Os"+"car" str = "Hello"+ CHR(32) + c + "!" print str


Result is: Hello Oscar

Comments

Everything in a line after // is deemed to be a comment

menu = MenuGetCurSel() // VTS menu 1..255, VMG menu 10001..10255


Whole line can be just a comment

// ****** The loop starts here ********

You can comment block of the text with /* and */

/* This text is just a comment It will never run

  • /

Language.

The whole language can be divided into two parts. One are commands of the basic language - the definition of the language. The other part are functions that are specific to DVD-lab.

CORE of language

Commands Syntax example Description
for to next for x=1 to 10

...

next x
loop, can be nested
if then else endif if (x==0) then

.....
else
......

endif
condition, can be nested
print print "Variable ", a, "Other Variable ", b print to Output window or if run directly show a message
print msg print msg "Variable ", a always show a message
trace trace "Variable ", a print only to output window, if run directly nothing is shown (good for debugging)
input input "Enter value", a Input box for multiple parameters
end End of the script
goto goto 100 got label 100
gosub gosub 100 goto subroutine label 100
return return from subroutine

Defined functions

Functions Syntax example Description
RND a = RND(5) random value 0...5
INT a = INT(b) integer value from float
FLOAT a = FLOAT(b) create float from integer
CHR c = CHR(32) generates character from ascii number (32 is space for example)
ABS a = ABS(b-5) absolute value
STR c = STR(5) Convert integer number to string. In our example the C will become c= "5"
sin a =sin(3.14) Sine
cos a =cos(3.14) Cosine
MIN a = MIN(b,c) minimum value from two parameters
MAX a = MAX(b,c) maximum value from two parameters
RGB color = RGB(255,0,0) color value from red, green, blue components (in our example result is red color)
GETR

GETG

GETB
red = GETR(color) Get red, green or blue component from color value
VMG firstVMGmenu = VMG(1) adds 10000 to the parameter. For menu coding, see more <a href="lt_commands.htm">functions</a>
LEFT string = LEFT(input, x) gets first x character from left of the input string
RIGHT string = RIGHT(input, x) gets first x character from right of the input string
LOW string = LOW(string1) convert the string to lowercase
Predefined Values
TRUE
FALSE
1
0
NULL 0

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