Compilare: main.cpp: In function 'bool var()': main.cpp:41:19: warning: array subscript has type 'char' [-Wchar-subscripts] r = v[x[i]]; ^ main.cpp: In function 'int main()': main.cpp:78:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i<strlen(buff); i++) ~^~~~~~~~~~~~~ main.cpp:120:15: warning: array subscript has type 'char' [-Wchar-subscripts] v[c[k]] = !v[c[k]]; ^ main.cpp:120:26: warning: array subscript has type 'char' [-Wchar-subscripts] v[c[k]] = !v[c[k]]; ^