But for simply checking if the length is zero, General, since LenB returns the byte count in the VB double-byte strings Note that you should not replace Len by LenB in So the speed nearly doubles if you are using LenB instead of comparing the Here are the times for doing it 10 million times on our test system: If "ABC" = "" 0.73 s If "ABC" = vbNullString 0.58 s
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In a pointer to a string with zero length however, not all API/DLL functionsĬhecking if a string is empty 10 million times can also be done in different Note that the predefined constant vbNullString is not exactly the same as anĮmpty string, but it can be used as an equivalent and even returns true whenĬomparing vbNullString = "" (while vbNullString is a null pointer, "" results The improvement when using vbNullString is significant: e$ = "" 1.51 s While absolute times may again differ on your system, Assigning and testing empty stringsĪ loop assigning an empty string to a string variable 10 million times gives But take care: AscW may return valuesĪbove 255, depending on the character set used, and this is not always easy to While the difference between Chr and ChrW is marginal, AscW
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VB-internal 16-bit Unicode characters to 8-bit ANSI codes or vice versa, theyĪre a bit faster. There are also speed differences between Asc and AscW, and Chr$ and ChrW$.īecause the functions with a W (for wide) do not have to convert the Right RightB RTrim Space Str String Trim UCase To avoid the unnecessary type conversion:Ĭhr ChrB CurDir Dir Format Hex Input InputB LCase Left LeftB Mid MidB Oct So a dollar symbol should be added behind all functions returning a string
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Times on a test PC shows significant timing differences: e$ = mid("ABC", 2) 5.0 s It willĮxplicitly enforce a string value to be returned. But without the $, VB will return a variant value and has to Representing the string type is more or less implicit for string manipulatingįunctions. One might expect that Mid$( ) and Mid( ) are the same and the dollar symbol Use the dollar symbol for string functions Please note that the given CPU times shouldīe read as relative values which greatly depend on the PC speed. A few simple tricks make execution speed even faster. Overflows and null pointer problems, well-known to most C programmers, are In other languages and also improve stability: Crashes caused by buffer Especially its string concept and string functions make life easier than While manyĪpplications at Shamrock were written in C and C++, some were also created in Microsoft Visual Basic is a popular programming language. If list.ColumnAlignment(cx)=list.AlignCenter thenĬall pdf.SetTextRect ex,y+ 23+cy* 21,columnwidths(cx), 21Ĭall pdf.WriteFText pdf.ktaCenter, list.Cell(cy,cx)Įlseif list.ColumnAlignment(cx)=list.AlignRight thenĬall pdf.SetTextRect ex, y+ 23+cy* 21, columnwidths(cx)- 3, 21Ĭall pdf.WriteFText pdf.ktaRight, list.Cell(cy,cx)Ĭall pdf.SetTextRect ex+ 3,y+ 23+cy* 21, columnwidths(cx), 21Ĭall pdf.WriteFText pdf.ktaLeft, list.Cell(cy,cx)Ĭall pdf.setfont font, pdf.kfsBold, size, true, pdf.kcp1252Ĭall pdf.SetTextRect ex,y+ 2,columnwidths(cx), 21Ĭall pdf.WriteFText pdf.ktaCenter, list.Heading(cx)Ĭall pdf.SetTextRect ex,y+ 2,columnwidths(cx)- 3, 21Ĭall pdf.WriteFText pdf.ktaRight, list.Heading(cx)Ĭall pdf.SetTextRect ex+ 3,y+ 2,columnwidths(cx), 21Ĭall pdf.WriteFText pdf.ktaLeft, list.Visual Basic Programs Simple tricks for VB optimization Remainingspace=remainingspace-columnwidthįor i as integer=1 to list.ColumnCount- 1Ĭall pdf.SetFont font,pdf.kfsNone, size, true, pdf.kcp1252įor cx as integer=0 to list.ColumnCount- 1 Sub DrawListbox(pdf as dynapdfmbs, list as listbox, x as integer, y as integer, width as integer)ĭim height as integer = list.ListCount* 21+ 22Ĭall pdf.Rectangle x,y,width- 1, 21, pdf.kfmFillĬall pdf.Rectangle x,y,width- 1,height,pdf.kfmStrokeĭim cw(- 1) as string = split(List.ColumnWidths, ",")ĭim remainingspace as integer = width-List.ColumnCount- 1Ĭolumnwidth=val(s)*remainingspace/starcount MsgBox "Can't write file to "+outfile.AbsolutePath
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This message will be suppressed on further calls in /kunden//webseiten/monkeybreadsoftware-video/rbformat/rbcode.php on line 244ĭim outfile as FolderItem=GetFolderItem( "table.pdf")Ĭall pdf.CreateNewPDF( nil) // the output file is created laterĬall pdf.SetDocInfo pdf.kdiCreator, "Realbasic test application"Ĭall pdf.SetDocInfo pdf.kdiTitle, "My first table output"ĭrawListbox pdf, Listbox1, 50, 50, pdf.GetPageWidth- 100 Deprecated: The each() function is deprecated.