foo.cc: In function 'int main()':
foo.cc:64:7: warning: unused variable 'k1' [-Wunused-variable]
   64 |   int k1 = A.BinSearch2(0, n-1, x);
      |       ^~
foo.cc: In member function 'int IntArray::BinSearch2(int, int, int)':
foo.cc:38:2: warning: control reaches end of non-void function [-Wreturn-type]
   38 |  }
      |  ^

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