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--- vbs:lastlinesoftextfile [2013/01/24 08:50] – rlunaro
+++ vbs:lastlinesoftextfile [2022/12/02 21:02] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
+====== Read the Last Lines of a Text File ======
+The program works smoothly even on files of twenty thousand lines. It simply read lines, keeping in memory the last N lines. When it reaches the end of the stream, it return the last N lines kept.
+<code visual basic>
+' read all the content of a log file and
+' put it into a string.
+function log2str( byval filename,  byval lastLines )
+    dim fso
+    dim file
+    dim lines()
+    dim linenum
+    dim lastWrittenLine
+    dim out
+    set fso = createobject( "scripting.filesystemObject" )
+    set file = fso.openTextFile( filename )
+    redim lines(lastLines)
+    linenum = 0
+    lastWrittenLine = -1
+    do while not file.atEndOfStream
+        lines( linenum ) = file.readLine
+        lastWrittenLine = linenum
+        linenum = (linenum + 1 ) mod lastLines
+    loop ' not file.atEndOfStream
+    if lastWrittenLine > 0 then
+        linenum = (lastWrittenLine + 1) mod lastLines
+        do
+            if lines(linenum) <> "" then
+                out = out & lines(linenum) & vbCrLf
+            end if ' lines(linenum) <> ""
+            linenum = (linenum + 1 ) mod lastLines
+        loop until linenum = (lastWrittenLine + 1)
+    end if ' lastWrittenLine
+    ' return all the content
+    log2str = out
+end function ' log2str
+</code>