Compilare: user.cpp: In function ‘int factor()’: user.cpp:78:19: warning: array subscript has type ‘char’ [-Wchar-subscripts] v[s[p]]=!v[s[p]]; ^ user.cpp:78:28: warning: array subscript has type ‘char’ [-Wchar-subscripts] v[s[p]]=!v[s[p]]; ^ user.cpp:79:17: warning: array subscript has type ‘char’ [-Wchar-subscripts] r=v[s[p]]; ^ user.cpp: In function ‘int main()’: user.cpp:144:9: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] s[i]=NULL; ^ user.cpp:151:11: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(v[c]==0) ^ user.cpp:152:12: warning: array subscript has type ‘char’ [-Wchar-subscripts] v[c]=1; ^ user.cpp:154:12: warning: array subscript has type ‘char’ [-Wchar-subscripts] v[c]=0; ^ user.cpp: In function ‘int factor()’: user.cpp:84:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp:72:21: warning: ‘r’ may be used uninitialized in this function [-Wmaybe-uninitialized] return !r; ^