test18.cpp: In function 'int func3(Data1*, Data1*)':
test18.cpp:28:11: warning: Using parameter 'ptr1' without checking for null pointer
     ptr1->val = 100;
           ^
test18.cpp: In function 'void func4(Data1*, Data1*)':
test18.cpp:40:11: warning: Using parameter 'ptr1' without checking for null pointer
     ptr1->val = 100;
           ^