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--- root:troubleshooting [2010/11/09 16:02] – nchiap
+++ root:troubleshooting [2013/06/14 12:14] (current) – nchiap
@@ Line 1: / Line 1: @@
-====== Writing Root-files ======
+====== Root-files ======
-<code C>
-TFile* inputFile = TFile::Open("myInputFile.root");
+Root-files can be the source of various problems.
-TFile* outputFile = new TFile("myOutputFile.root", "RECREATE");
+Usually they are caused by hidden changes in the internal state of ROOT.
-// your code
+ROOT stores the active directory and uses this to create new objects and look for existing ones.
-outputFile->Write();
+The active directory is changed when a new file is opened.
-</code>
+This can lead to unexpected behaviours and hard to trace bugs.
 ===== Empty Files =====
@@ Line 17: / Line 17: @@
 outputFile->Write();
 </code>
+but instead do:
+<code C>
+TFile* inputFile = TFile::Open("myInputFile.root");
+TFile* outputFile = new TFile("myOutputFile.root", "RECREATE");
+// your code
+outputFile->Write();
+</code>

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