Compilare: user.cpp: In function ‘int main()’: user.cpp:15:12: warning: array subscript has type ‘char’ [-Wchar-subscripts] s[++top]=t[0]; ^ user.cpp:17:17: warning: NULL used in arithmetic [-Wpointer-arith] while(t[i]!=NULL) ^ user.cpp:19:33: warning: array subscript has type ‘char’ [-Wchar-subscripts] while(top>=0&&t[i]>s[top]&&n-i>=m-top)top--; ^ user.cpp:20:27: warning: array subscript has type ‘char’ [-Wchar-subscripts] if(top<m-1)s[++top]=t[i]; ^ user.cpp:23:12: warning: array subscript has type ‘char’ [-Wchar-subscripts] s[++top]=NULL; ^ user.cpp:23:13: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] s[++top]=NULL; ^