Compilare: user.cpp: In function ‘int main()’: user.cpp:22:19: warning: array subscript has type ‘char’ [-Wchar-subscripts] w[v[j]]++; ^ user.cpp:8:13: warning: unused variable ‘k’ [-Wunused-variable] int i,j,k,n,x1,x; ^ user.cpp:32:15: warning: iteration 4u invokes undefined behavior [-Waggressive-loop-optimizations] w[j]=0; ^ user.cpp:31:9: note: containing loop for(j='a';j<='z';j++) ^ user.cpp:25:15: warning: iteration 4u invokes undefined behavior [-Waggressive-loop-optimizations] if(w[j]>1) ^ user.cpp:24:9: note: containing loop for(j='a';j<='z';j++) ^ /tmp/cczC7jUe.o: In function `main': user.cpp:(.text.startup+0x98): warning: the `gets' function is dangerous and should not be used.