Compilare: user.cpp: In function ‘int main()’: user.cpp:38:11: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] s[p-s]=NULL; ^ user.cpp:27:25: warning: unused variable ‘c’ [-Wunused-variable] char s[256],s2[255],c,S,*p; ^ user.cpp:27:27: warning: unused variable ‘S’ [-Wunused-variable] char s[256],s2[255],c,S,*p; ^