For example, create a sample log file with 10,000 lines, and modify the script so it stores just the value of line 9999 in a variable. Like we said, not very elegant, but it works.
We weren’t able to use any nifty shortcuts, but we achieved our goal: we managed to get the value of line 4 into the variable strLine.
That’s what we do here: strLine = objTextFile.ReadLineįor the purposes of our demonstration script, we then echo the value of strLine and close the text file. We call the ReadLine method again, only this time we store the contents of that line in the variable strLine. The third time through – that’s right, we read line 3, and then drop down to line 4, the line we’re interested it.Īt this point, we’re done with our loop. The second time through, we read line 2, and drop down to line 3. The first time through the loop, it calls the ReadLine method this reads the first line in the text file (although we don’t do anything with the information we read), and then automatically drops us down to the next line in the file (line 2).
#How to append to text file labview 2012 code#
That’s exactly what this block of code does.
Why? Well, remember, all we’re really interested in is line 4, but the FileSystemObject won’t let us go directly to line 4 instead, we have to get through lines 1, 2, and 3 first. Inside that loop, we use the ReadLine method to read the current line in the text file. We then create a For Next loop that loops from 1 to 3. So what’s going on here? Well, we begin by creating an instance of the FileSystemObject and opening the file Mylogfile.log for reading. Set objTextFile = objFSO.OpenTextFile(“mylogfile.log”, ForReading) Set objFSO = CreateObject(“Scripting.FileSystemObject”) We can’t jump to line 4 directly, but we can achieve the desired result by using a script like this: Const ForReading = 1 We want to store the contents of line 4 – and just the contents of line 4 – in a variable. For the sake of brevity, let’s consider a simple text file with five lines: 1 Now, that doesn’t mean we can’t store just the value of line 16 in a variable it just means we have to use a somewhat less-than-elegant approach. There’s no way to quickly jump to a specified line. The FileSystemObject – which provides most of the text-handling capabilities available to scripters – can only start with line 1 of a file and then works its way down. You might think that WSH or VBScript or some scripting object would have a method in which you could say, “Hey, go read line 16 and only line 16 of this file.” No such luck.
#How to append to text file labview 2012 windows#
Of course, the reason we get so many questions about text files is the fact that the scripting technologies built into Windows don’t have very sophisticated text handling capabilities. People always ask if we’ve ever met Bill Gates the truth is we always try to avoid Bill Gates, because we’re afraid he’ll ask us questions about text files.
You know we haven’t answered a question about text files in awhile, and that’s not something we should brag about after all, it sometimes seems like every other question we get has to do with reading from and writing to text files. Hey, Scripting Guy! How can I read only a specific line in a text file? For example, how can I write a script that reads only line 16 in a text file and then stores the value of that line in a variable?
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