Compilare: user.cpp: In function ‘void read()’: user.cpp:24:23: warning: format ‘%s’ expects argument of type ‘char*’, but argument 2 has type ‘char (*)[20]’ [-Wformat=] scanf("%s",&nr); ^ user.cpp:25:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < strlen(nr); i++) { ^ user.cpp:30:23: warning: format ‘%s’ expects argument of type ‘char*’, but argument 2 has type ‘char (*)[20]’ [-Wformat=] scanf("%s",&nr); ^ user.cpp:31:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < strlen(nr); i++) { ^ user.cpp:20:17: warning: unused variable ‘x’ [-Wunused-variable] long double x, y; ^ user.cpp:20:20: warning: unused variable ‘y’ [-Wunused-variable] long double x, y; ^