QBJS - Fun Facts!

[dbox]

Starting a thread here to post fun facts about QBJS that you might not know.

Fun Fact #1 - You can define optional parameters!

Code: (Select All)

PrintLines "First Test"
PrintLines "Second Test", 4
PrintLines "Third Test", , " -> "

Sub PrintLines (msg As String, lines As Integer, prefix As String)
    If lines = undefined  Then lines = 2   ' default to 2 lines
    If prefix = undefined Then prefix = "" ' default to blank prefix
   
    Dim i As Integer
    For i = 1 To lines
        Print prefix; msg
    Next i
End Sub

Output:

Code: (Select All)

First Test
First Test
Second Test
Second Test
Second Test
Second Test
-> Third Test
-> Third Test

Try it out on QBJS

[mnrvovrfc]

   

[mnrvovrfc]

STRING$() function has weird behavior in QBJS. Is this on purpose?

Because I tried to test with the following code:

Code: (Select All)

print string$(80, 42)
print string2$(80, 42)
print string$(40, "*+-")
print string2$(40, "*+-")
print string2$(40, "*+-", 2)
print string2$(20, "*+-", 3)
end

function string2$(quant as integer, astr as string, numchar as integer)
    dim i as integer, sret$
    if astr = undefined then astr = chr$(32)
    if numchar = undefined then numchar = 1
    for i = 1 to quant
        sret$ = sret$ + left$(astr, numchar)
    next
    string2$ = sret$
end function

For the first line, I got "42" replicated 40 times. In QuickBASIC and "clones" it gives me 80 asterisks.

Even weirder, I do:

Code: (Select All)

print string$(10, 432)

and the result is "4324324324". Not sure but it's supposed to flag an error that the second parameter must be type byte.

Otherwise this is pretty neat and I could finally shelf my REPEAT$(). LOL.

[dbox]

STRING$() function has weird behavior in QBJS. Is this on purpose?

Good catch! Looks like I missed the fact that the STRING$ function can take either a string or a character code.  Fix will be included in the next release.

[dbox]

Fun Fact #2 - Custom types can be returned from functions!

Code: (Select All)

Screen 12

Type Circ
    x As Integer
    y As Integer
    r As Integer
    c As Integer
End Type

Dim i As Integer
Dim c As Circ
Do
    Cls
    For i = 1 To 100
        c = MakeCircle
        Circle (c.x, c.y), c.r, c.c
    Next i
    _Limit 10
Loop

Function MakeCircle
    Dim c As Circ
    c.x = Rnd * 640
    c.y = Rnd * 480
    c.r = Rnd * 100 + 10
    c.c = Rnd * 14 + 1
    MakeCircle = c
End Function

Try it on QBJS

[vince]

you can write things without brackets ie

Code: (Select All)

cmul q, q, g
cdiv p, p, q


sub cmul( w(), z1(), z2() )
    x1 = z1(0)
    y1 = z1(1)
    a1 = z2(0)
    b1 = z2(1)

    w(0) = x1*a1 - y1*b1
    w(1) = x1*b1 + y1*a1
end sub

sub cdiv( w(), z1(), z2() )
    x1 = z1(0)
    y1 = z1(1)
    a1 = z2(0)
    b1 = z2(1)

    d1 = a1*a1 + b1*b1
    w(0) = (x1*a1 + y1*b1)/d1
    w(1) = (y1*a1 - x1*b1)/d1
end sub

[dbox]

Fun Fact #3 - QBJS has native support for associative arrays (dictionary).

This feature is sometimes also known as a map or hashmap.

Code: (Select All)

Dim colors() As _Unsigned Long

colors("brick red") = &HFFC62D42
colors("electric lime") = &HFFCCFF00
colors("metalic sunburst") = &HFF9C7C38

Cls , 15
Line (10, 10)-(100, 100), colors("electric lime"), BF
Line (200, 200)-(300, 300), colors("brick red"), BF
Circle (200, 100), 50, colors("metalic sunburst")

Try it on QBJS

[bplus]

Ah so that's how dictionary's are supposed to be used. I was wondering how I might apply the dictionary code I was working on yesterday. So I need to rename the Function that does a Value Lookup from a Key to something short and easy and maybe do a value conversion for numbers. Thanks for new ideas!

Now I wonder, could I do a whole program with variables and values from a dictionary? Bet I can! Be fun to try anyway

Ha! The JS part is really showing up the QB part ;-))

[mnrvovrfc]

Code: (Select All)

Dim colors() As _Unsigned Long

colors("brick red") = &HFFC62D42
colors("electric lime") = &HFFCCFF00
colors("metalic sunburst") = &HFF9C7C38

Cls , 15
Line (10, 10)-(100, 100), colors("electric lime"), BF
Line (200, 200)-(300, 300), colors("brick red"), BF
Circle (200, 100), 50, colors("metalic sunburst")

This could be faked as function, and on 64-bit it's faster than any "dictionary" implementation:

Code: (Select All)

FUNCTION colors~& (mycolor$)
    DIM iret AS _UNSIGNED LONG
    IF mycolor$ = "brick red" THEN
        iret = &HFFC62D42
    ELSEIF mycolor$ = "electric lime" THEN
        iret = &HFFCCFF00
    ELSEIF mycolor$ = "metallic sunburst" THEN
        iret = &HFF9C7C38
    ELSE
        iret = 0
    END IF
    colors~& = iret
END FUNCTION

[CharlieJV]

Code: (Select All)

Dim colors() As _Unsigned Long

colors("brick red") = &HFFC62D42
colors("electric lime") = &HFFCCFF00
colors("metalic sunburst") = &HFF9C7C38

Cls , 15
Line (10, 10)-(100, 100), colors("electric lime"), BF
Line (200, 200)-(300, 300), colors("brick red"), BF
Circle (200, 100), 50, colors("metalic sunburst")

This could be faked as function, and on 64-bit it's faster than any "dictionary" implementation:

Code: (Select All)

FUNCTION colors~& (mycolor$)
    DIM iret AS _UNSIGNED LONG
    IF mycolor$ = "brick red" THEN
        iret = &HFFC62D42
    ELSEIF mycolor$ = "electric lime" THEN
        iret = &HFFCCFF00
    ELSEIF mycolor$ = "metallic sunburst" THEN
        iret = &HFF9C7C38
    ELSE
        iret = 0
    END IF
    colors~& = iret
END FUNCTION

Sure, but the "dictionary" code is way easier to read, and much better for filling the dictionary with values coming from DATA statements or from files.  The data source, as-is, works as documentation.

If speed is critical, then pick the speedy one.  If flexibility and readability are critical, then go for the dictionary.