/in/ex4.cpp:2:18: error: extra tokens at end of #include directive [-Werror]
 #include <string>]
                  ^
/in/ex4.cpp: In function 'int main()':
/in/ex4.cpp:31:30: error: ISO C++ forbids variable length array 'blocks' [-Werror=vla]
     Block blocks[width*length];
                              ^
/in/ex4.cpp:25:9: error: unused variable 'ptr' [-Werror=unused-variable]
     int ptr=0;
         ^~~
/in/ex4.cpp:31:11: error: variable 'blocks' set but not used [-Werror=unused-but-set-variable]
     Block blocks[width*length];
           ^~~~~~
cc1plus: all warnings being treated as errors