Compilare: user.cpp: In function ‘int main()’: user.cpp:15:42: warning: array subscript has type ‘char’ [-Wchar-subscripts] for(ch='a'; ch<='z'; ++ch) ap[ch]=0; k=0; ^ user.cpp:16:38: warning: array subscript has type ‘char’ [-Wchar-subscripts] for(i=0; i<l; ++i) ++ap[s[i]]; ^ user.cpp:17:44: warning: array subscript has type ‘char’ [-Wchar-subscripts] for(ch='a'; ch<='z'; ++ch) if(ap[ch]%2) ++k; ^ user.cpp:24:27: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(ap[s[k]]!=1) ^ user.cpp:34:38: warning: array subscript has type ‘char’ [-Wchar-subscripts] ap[s[k-1]]-=2; ^ /tmp/ccvs0O5D.o: In function `main': user.cpp:(.text.startup+0x8b): warning: the `gets' function is dangerous and should not be used.