foo.cc:9:1: error: expected initializer before 'void'
    9 | void CreatBiTree(BiTree& T)
      | ^~~~
foo.cc:25:23: error: variable or field 'PreOrderTraverse' declared void
   25 | void PreOrderTraverse(BiTree T)
      |                       ^~~~~~
foo.cc:25:23: error: 'BiTree' was not declared in this scope
foo.cc: In function 'int main()':
foo.cc:36:5: error: 'BiTree' was not declared in this scope
   36 |     BiTree T;
      |     ^~~~~~
foo.cc:37:17: error: 'T' was not declared in this scope
   37 |     CreatBiTree(T);
      |                 ^
foo.cc:37:5: error: 'CreatBiTree' was not declared in this scope
   37 |     CreatBiTree(T);
      |     ^~~~~~~~~~~
foo.cc:39:5: error: 'PreOrderTraverse' was not declared in this scope
   39 |     PreOrderTraverse(T);
      |     ^~~~~~~~~~~~~~~~

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