test24.c: In function 'func1':
test24.c:33:5: warning: Using parameter 'ptr1' without checking for null pointer
     ptr1();
     ^
test24.c: In function 'func4':
test24.c:51:9: warning: Using parameter 'ptr1' without checking for null pointer
     ptr1->fptr1(ptr2);
         ^
test24.c: In function 'func6':
test24.c:63:11: warning: Using parameter 'ptr1' without checking for null pointer
     (*ptr1[1])(data);
           ^
test24.c: In function 'func8':
test24.c:86:9: warning: Using parameter 'fptr' without checking for null pointer
     fptr[1]("", "");
         ^