对SVN diff命令的输出感到困惑

Question

I'm not a svn guru so sorry for the simple question.

Now, when I write a svn diff -r 1:2 file:///home/svn/myproject/cs112 I've expected It gives me the differences between revision1 of cs112 and revision 2. However the output of this commad is :

Index: lab1/firstFile.c
===================================================================
--- lab1/firstFile.c    (revision 0)
+++ lab1/firstFile.c    (revision 2) 
@@ -0,0 +1,6 @@
+#include "stdio.h"
+int main
+{
+printf("first sentence");
+}

Why it writes (revision 0) and (revision 2) ?? and also what is the meaning of @@ -0,0 +1,6 @@ ?? thanks in advance

Answer 1

The file in question did not exist in revision 1 (it was probably added at revision 2).

You do not have to worry about the exact meaning of the @@ strings, it just helps svn to locate the changes. In fact, it denotes the position (line number and number of following lines) in the file where the changes happened.