Compilare: main.cpp: In function 'int main()': main.cpp:22:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (len!=strlen(b)) ~~~^~~~~~~~~~~ main.cpp:28:25: warning: array subscript has type 'char' [-Wchar-subscripts] fra[a[i]]++; ^ main.cpp:29:25: warning: array subscript has type 'char' [-Wchar-subscripts] frb[b[i]]++; ^