test18.cpp: In function 'int func3(Data1*, Data1*)':
test18.cpp:28:20: warning: Using variable 'ptr1' without checking for null pointer
     ptr1->val = 100;
                    ^
test18.cpp:28:20: warning: Using variable 'ptr1' without checking for null pointer
test18.cpp: In function 'void func4(Data1*, Data1*)':
test18.cpp:40:20: warning: Using variable 'ptr1' without checking for null pointer
     ptr1->val = 100;
                    ^
test18.cpp:40:20: warning: Using variable 'ptr1' without checking for null pointer