From 53043b9f428aa51feef279864d91ae7afca3b66e Mon Sep 17 00:00:00 2001
From: Alessandro Ferro <49845537+xfarrow@users.noreply.github.com>
Date: Fri, 19 Mar 2021 11:30:28 +0100
Subject: [PATCH] lezione 3

---
 teoria/enum_istream_ostream.cpp | 26 ++++++++++++++++++++++++++
 teoria/enumeration.cpp          | 27 +++++++++++++++++++++++++++
 teoria/friendFunction.cpp       | 19 +++++++++++++++++++
 teoria/istream_ostream.cpp      | 17 +++++++++++++++++
 teoria/struct.cpp               |  3 ++-
 5 files changed, 91 insertions(+), 1 deletion(-)
 create mode 100644 teoria/enum_istream_ostream.cpp
 create mode 100644 teoria/friendFunction.cpp
 create mode 100644 teoria/istream_ostream.cpp

diff --git a/teoria/enum_istream_ostream.cpp b/teoria/enum_istream_ostream.cpp
new file mode 100644
index 0000000..1cea588
--- /dev/null
+++ b/teoria/enum_istream_ostream.cpp
@@ -0,0 +1,26 @@
+#include<iostream>
+using namespace std;
+
+enum class Color{red, white, green, black};
+
+ostream& operator<<(ostream& outputStream, const Color& color){ //la keyword const non è obbligatoria, ma meglio metterla
+  switch(color){
+    case Color::red:
+      outputStream<<"Rosso";
+      break;
+    case Color::white:
+      outputStream<<"Bianco";
+      break;
+    case Color::green:
+      outputStream<<"Verde";
+      break;
+    case Color::black:
+      outputStream<<"Nero";
+  }
+  return outputStream;
+}
+int main(){
+  Color myColor = Color::red;
+  cout<<myColor<<endl;
+  return 0;
+}
diff --git a/teoria/enumeration.cpp b/teoria/enumeration.cpp
index e69de29..33ae81f 100644
--- a/teoria/enumeration.cpp
+++ b/teoria/enumeration.cpp
@@ -0,0 +1,27 @@
+#include <iostream>
+using namespace std;
+
+enum class Color1{green, white, red};
+enum class Color2{black, blue, brown, green, red};
+
+enum Color3{rosso, arancione};
+//enum Color4{rosso, viola}; //errore, rosso già dichiarato
+
+int main(){
+
+  // Posso accedere ai valori di Color3 come fossero variabili globali
+  cout<<rosso<<" "<<arancione<<endl; // 0 1
+
+  // Non posso accedere direttamente ai valori di Color1 e Color2
+  //cout<<green;
+
+  //Ma devo richiamarli in questo modo:
+  cout<<(int)Color1::green<<endl; // a differenza dell'enum normale, devo fare un cast
+
+  //if(rosso == Color1::green) //errore
+  if(rosso == (int)Color1::green) cout<<"Cast obbligatorio"<<endl;
+
+  Color1 mioColore = Color1::green;
+  if(mioColore == Color1::green) cout<<"Tipi uguali direttamente confrontabili"<<endl;
+
+}
diff --git a/teoria/friendFunction.cpp b/teoria/friendFunction.cpp
new file mode 100644
index 0000000..3972430
--- /dev/null
+++ b/teoria/friendFunction.cpp
@@ -0,0 +1,19 @@
+#include<iostream>
+using namespace std;
+
+struct Studente{
+  friend void printSecureNumber(Studente); // posso mettere questa linea ovunque all'interno della struct
+
+  string nome;
+  string cognome;
+  private:
+        int secureNumber = 999;
+};
+void printSecureNumber(Studente s){
+  cout<<s.secureNumber<<endl;
+}
+int main(){
+  Studente st;
+  printSecureNumber(st);
+  return 0;
+}
diff --git a/teoria/istream_ostream.cpp b/teoria/istream_ostream.cpp
new file mode 100644
index 0000000..01c106c
--- /dev/null
+++ b/teoria/istream_ostream.cpp
@@ -0,0 +1,17 @@
+#include <iostream>
+using namespace std;
+struct Studente{
+  string nome, cognome, matricola;
+  int annoCorso;
+};
+ostream& operator<<(ostream& outputStream, const Studente& st){ //la keyword const non è obbligatoria, ma meglio metterla
+  return outputStream<<st.nome<<" "<<st.cognome<<" "<<st.matricola<<" "<<st.annoCorso<<endl;
+}
+istream& operator>>(istream& inputStream, Studente& st){
+  return inputStream>>st.nome>>st.cognome>>st.matricola>>st.annoCorso;
+}
+int main(){
+  Studente s;
+  cin>>s;
+  cout<<s;
+}
diff --git a/teoria/struct.cpp b/teoria/struct.cpp
index f1079f7..c9cc564 100644
--- a/teoria/struct.cpp
+++ b/teoria/struct.cpp
@@ -9,6 +9,7 @@ int main(){
 }
 
 void studentStructWithConstructor(){
+
   struct StudentNoDefaultConstructor{
     string nome, cognome, matricola;
     int annoCorso;
@@ -46,7 +47,7 @@ void studentStruct(){
     int annoCorso;
   };
   struct Student st1{"Alan","Turing","N86000000",1};
-  struct Student st2 = {"Kurt","Godel","N86000001",1};
+  struct Student st2 = {"Kurt","Godel","N86000001",1}; // non preferibile
   //Student st3("Kurt","Godel","N86000001",1); // errore, richiede esplicitamente un costruttore
   struct Student st4;
   struct Student st5();