added lecture 3

Author: davydenk

Diff for: README.md

@@ -34,13 +34,17 @@ Giovedì 06/10 – Aula 128-129
  - review of last homework
  - survival crush course on git
 
-Martedì 11/10 – Aula 128-129
+Martedì 11/10 – cancelled
 
-Giovedì 13/10 – Aula 128-129
+Giovedì 13/10 – cancelled
 
-Martedì 18/10 – Aula 004
+Martedì 18/10 – zoom
+ - general program structure
+ - Makefiles
+ - operator overloads
+ - working with text files
 
-Giovedì 20/10 – Aula 128-129
+Giovedì 20/10 – zoom
 
 Martedì 25/10 – Aula 128-129
 
@@ -66,7 +70,7 @@ Martedì 29/11 – Aula 128-129
 
 Giovedì 01/12 – Aula 128-129
 
-Martedì 06/12 – Aula 004
+Martedì 06/12 – AULA 139
 
 Giovedì 08/12 – Festa
 

Diff for: examples/files.cpp

@@ -0,0 +1,31 @@
+#include <iostream>
+#include <fstream>
+
+int main(){
+    //you can do the same things as with std::cout and std::cin
+
+    //this will create "test.txt" if it doesn't exist or overwrite if it does
+    std::ofstream filevar("test.txt");
+    //filvar.open("name.txt")
+    filevar << "1 2 3"<<std::endl;
+    filevar.close();
+    
+    int a{0},b{0},c{0};
+    std::ifstream filevar2("test.txt");
+    //better to check if it worked, cause it won't complain
+    if(filevar2){
+        filevar2 >> a >>b >>c;
+    }else{
+        std::cout<<"failed opening the file"<<std::endl;
+    }
+   
+    std::cout<<a<< " " <<b <<" "<< c<<std::endl;
+    filevar2.close();
+    
+    //this will append instead of overwriting
+    filevar.open("test.txt", std::ios_base::app);
+    filevar << "1 2 3"<<std::endl;
+    filevar.close();
+    
+    return 0;
+}

Diff for: examples/hello_again/Makefile

@@ -0,0 +1,15 @@
+# This is a comment line
+CC=g++
+# This is a folder to look for header files
+INCDIR=include
+# CFLAGS will be the options passed to the compiler.
+CFLAGS= -c -I$(INCDIR)
+
+hello.x: main.o hello.o
+	$(CC) main.o hello.o -o hello.x
+main.o: main.cpp
+	$(CC) $(CFLAGS) main.c
+src/hello.o: src/hello.c
+	$(CC) $(CFLAGS) hello.c
+clean:
+	rm -rf *.o *.x 

Diff for: examples/hello_again/Makefile2

@@ -0,0 +1,18 @@
+# This is a comment line
+CC=g++
+# where to look for headers:
+INCDIR=include
+OBJDIR=obj
+# CFLAGS will be the options passed to the compiler.
+CFLAGS= -c -I$(INCDIR)
+OBJECTS= main.o $(OBJDIR)/hello.o
+
+hello.x: $(OBJECTS)
+	$(CC) $(OBJECTS) -o $@
+main.o: main.cpp
+	$(CC) $(CFLAGS) main.cpp
+obj/%.o: src/%.cpp  
+	$(CC) $(CFLAGS) $^ -o $@
+clean:
+	rm -rf *.o *.x
+ 

Diff for: examples/hello_again/include/hello.hpp

@@ -0,0 +1,3 @@
+#pragma once
+
+ void hello();

Diff for: examples/hello_again/main.cpp

@@ -0,0 +1,6 @@
+#include "hello.hpp"
+
+int main(){
+    hello();
+    return 0;
+}

Diff for: examples/hello_again/src/hello.cpp

@@ -0,0 +1,7 @@
+#include <iostream> 
+#include "hello.hpp"
+
+void hello(){
+     std::cout<<"Hello, World!"<<std::endl;
+}
+ 

Diff for: examples/operators1.cpp

@@ -0,0 +1,73 @@
+#include <iostream>
+#include <cmath>
+
+//example of overloading arithmetic operators
+
+class CCoords{
+    double x;
+    double y;
+public:
+    CCoords(){
+      x=0;y=0;  
+    }    
+    CCoords(const double& x0,const double& y0):x(x0),y(y0){}
+    CCoords operator+(const CCoords& b) {
+        CCoords result;
+        result.x = x + b.x;
+        result.y = y + b.y;
+        return result;
+    }//operator+
+  /*  //this is a wrong way, as it becomes non-commutative
+    CCoords operator+(const int& b) {
+        CCoords result;
+        result.x = x + b;
+        result.y = y + b;
+        return result;
+    }//operator+
+   */ 
+   friend CCoords operator+(const CCoords& c, const int& b);
+   friend CCoords operator+(const int& b, const CCoords& c);
+    
+    //have to assume it can be non-integer
+    bool operator==(const CCoords& b) {
+        bool result{false};
+        if ((std::fabs(x-b.x)<10e-9) && (std::fabs(y-b.y)<10e-9)){
+            result=true;
+        }
+        return result;
+      }//operator==  
+    void print(){
+        std::cout<<"x is "<<x<<", y is "<<y<<std::endl;
+    }  
+      
+};
+
+
+CCoords operator+(const CCoords& c, const int& b){
+    CCoords result;
+    result.x=c.x+b;
+    result.y=c.y+b;
+    return result;
+};
+ 
+CCoords operator+(const int& b, const CCoords& c){
+    CCoords result;
+    result.x=c.x+b;
+    result.y=c.y+b;
+    return result;
+};
+
+int main(){
+  CCoords var(2,3),var2(4.4,9.1);
+  
+  auto var3=var + var2;
+  var3.print();
+  if(var2==var3){
+    std::cout<<"equal"<<std::endl;
+  }else{
+    std::cout<<"not equal"<<std::endl;
+  }
+  auto var4= var+2;
+  var4=2+var;
+  return 0;  
+}

Diff for: examples/operators2.cpp

@@ -0,0 +1,58 @@
+#include <iostream>
+#include <cmath>
+
+struct CCoords{
+    double x;
+    double y;
+    CCoords(){ x=0;y=0; }
+    CCoords operator+(const CCoords& b);
+    bool operator==(const CCoords& b); 
+    
+   //instead of a print function we can overload <<
+    //get a habit to make it a friend in case you change to proper private values
+    friend std::ostream& operator<<(std::ostream& os, const CCoords& c);
+    //a totally nonsense overload just to show that we can
+    void operator[](const int& N){
+        std::cout<<"What did you intend to do with calling [] on coordinates?..."<<std::endl;
+    } 
+    //another totally nonsense overload just to show that we can
+    void operator()(){
+        std::cout<<"What did you intend to do with calling () on coordinates?..."<<std::endl;
+    };
+};
+
+std::ostream& operator<<(std::ostream& os, const CCoords& c){
+    os<<"x is "<<c.x<<", y is "<<c.y<<std::endl;
+    return os;
+};
+
+
+int main(){
+  CCoords var,var2;
+  var.x=2; var.y=3;
+  var2.x=4.4; var2.y=9.1;
+  auto var3=var + var2;
+  std::cout<<var3<<std::endl;
+  var[7];
+  var();
+  return 0;  
+}
+
+
+
+bool CCoords::operator== ( const CCoords& b ) {
+       bool result{false};
+        if ((std::fabs(x-b.x)<10e-9) && (std::fabs(y-b.y)<10e-9)){
+            result=true;
+        }
+        return result;
+}//operator==  
+    
+
+CCoords CCoords::operator+ ( const CCoords& b ) {
+            CCoords result;
+        result.x = x + b.x;
+        result.y = y + b.y;
+        return result;
+}
+