Summary: Discusses how to convert data read from a text file into its proper data type.
I have a text file that I am outputting from a C++ program and then trying to use within Rhino to change a model. We have the model made up and know how to read in the text file and parse it with VBScript. What I am having trouble doing is connecting the two. Can I read the information the text file and assign it as a variable?
Yes you can. Consider the following VBScript subroutine that reads a text file:
Sub ReadTextFile Dim objFSO, objFile, strFileName, strLine Const ForReading = 1 strFileName = Rhino.OpenFileName("Open", "Text Files (*.txt)|*.txt|") If IsNull(strFileName) Then Exit Sub Set objFSO = CreateObject("Scripting.FileSystemObject") Set objFile = objFSO.OpenTextFile(strFileName, ForReading) While Not objFile.AtEndOfStream strLine = objFile.ReadLine Rhino.Print strLine Wend objFile.Close Set objFSO = Nothing End Sub
Note how every line that is read from the text file is assigned to the strLine variable before it is printed.
Everything read from a text file using VBScript comes in as a string data type. Thus, if you are expecting something that you have read to be an integer or a floating point number, then you will need to convert the string to that data type. For example, let's say that you have a text file appears as follows:
7 3.14159 Hello Rhino!
If you use VBScript to read this file, all three lines will be read in as strings. If you want line one to be read as an integer and line two to be read as a double, then you can do use some of VBScript's data conversion functions to convert the string to the proper data type. For example:
Dim nFirst, dblSecond, strThird nFirst = CInt(objFile.ReadLine) dblSecond = CDbl(objFile.ReadLine) strThird = objFile.ReadLine
Note, the above example does have have the limitation of you having to know what kind of data is on each line. If you think might not be possible to know what kind of data is on each line, then you might consider exporting a “data type identifier” along with the data from your C++ program. This way, when you read a line from VBScript, you will know what kind of data it is that you have.
VBScript's VarType function that will return a value indicating the type of variable. The possible values are as follows:
vbEmpty 0 Uninitialized (default) vbNull 1 Contains no valid data vbInteger 2 Integer subtype vbLong 3 Long subtype vbSingle 4 Single subtype vbSingle 5 Double subtype vbCurrency 6 Currency subtype vbDate 7 Date subtype vbString 8 String subtype vbObject 9 Object vbError 10 Error subtype vbBoolean 11 Boolean subtype vbVariant 12 Variant (used only for arrays of variants) vbDataObject 13 Data access object vbDecimal 14 Decimal subtype vbByte 17 Byte subtype vbArray 8192 Array
Thus, above text file written to included the data's type identifier would like like the following:
2;7 5;3.14159 8;Hello Rhino!
Now each line in the text file contains both the data type and the data. Using VBScript's Split function, we can separate the data type from the data. Then, it is just a matter of testing for the types of data that our script supports and then performing the proper data coersion. For example:
Dim strLine, arrLine, nType, vaValue strLine = objFile.ReadLine arrLine = Split(strLine, ";") nType = CInt(arrLine(0)) Select Case nType Case 2 vaValue = CInt(arrLine(1)) Case 3 vaValue = CLng(arrLine(1)) Case 4 vaValue = CSng(arrLine(1)) Case 5 vaValue = CDbl(arrLine(1)) Case 8 vaValue = arrLine(1) Case 11 vaValue = CBool(arrLine(1)) Case Else Rhino.Print "Unsupported data type." End Select