CSharp – for Statement
using System;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
int number = 5;
for(int i = 0; i < number; i++)
Console.WriteLine(i);
// the console will close if you press Return on the keyboard
Console.ReadLine();
}
}
}
The result is:
0
1
2
3
4
CSharp – while Statement
using System;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
int number = 0;
while(number < 5)
{
Console.WriteLine(number);
number = number + 1;
}
// the console will close if you press Return on the keyboard
Console.ReadLine();
}
}
}
The result is:
0
1
2
3
4
CSharp – Switch Statement
The switch statement is like a set of if statements. It’s a list of possibilities, with an action for each possibility, and an optional default action, in case nothing else evaluates to true.
using System;
namespace ConsoleApplication1
{
class Program
{
static void Main()
{
int caseSwitch = 1;
switch (caseSwitch)
{
case 1:
Console.WriteLine("Case 1");
break;
case 2:
Console.WriteLine("Case 2");
break;
// if case 1 and case 2 are false:
default:
Console.WriteLine("Default case");
break;
}
} // End Main()
}
}
How to create a loop:
...
case 4:
while (true)
Console.WriteLine("Endless looping. . . .");
...
CSharp – Variables and Data Types
You are required to inform the compiler about which data types you wish to use every time you declare a variable.
byte —> 0 .. 255
sbyte —> -128 .. 127
short —> -32,768 .. 32,767
ushort —> 0 .. 65,535
int —> -2,147,483,648 .. 2,147,483,647
uint —> 0 .. 4,294,967,295
long —> -9,223,372,036,854,775,808 .. 9,223,372,036,854,775,807
ulong —> 0 .. 18,446,744,073,709,551,615
float —> -3.402823e38 .. 3.402823e38
double —> -1.79769313486232e308 .. 1.79769313486232e308
decimal —> -79228162514264337593543950335 .. 79228162514264337593543950335
char —> a Unicode character.
string —> a string of Unicode characters.
bool —> true or false.
object —> an object.
Example with strings:
// Working with strings
using System;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
// <datatype> <name>
string firstName = "John";
string lastName = "Doe";
Console.WriteLine("Name: " + firstName + " " + lastName);
Console.WriteLine("Please enter a new first name:");
// get new value from console
firstName = Console.ReadLine();
Console.WriteLine("New name: " + firstName + " " + lastName);
Console.ReadLine();
}
}
}
Example with math:
// Working with math
using System;
namespace ConsoleApplication1
{
class Program
{
static void Main()
{
// integer numbers
int number1, number2;
Console.WriteLine("Please enter a number:");
// It reads a string and converts it into an integer.
number1 = int.Parse(Console.ReadLine());
Console.WriteLine("Thank you. One more:");
number2 = int.Parse(Console.ReadLine());
Console.WriteLine("Adding the two numbers: " + (number1 + number2));
Console.ReadLine();
}
}
}
The constants refer to fixed values that the program may not alter during its execution.
The syntax is:
const <data_type> <constant_name> = value;
Example:
using System;
using System.Collections;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
const double pi = 3.14159; // constant declaration
double r;
Console.WriteLine("Enter Radius: ");
r = Convert.ToDouble(Console.ReadLine());
double areaCircle = pi * r * r;
Console.WriteLine("Radius: {0}, Area: {1}", r, areaCircle);
Console.ReadLine();
}
}
}
C++ Classes
Classes are an expanded concept of data structures: like data structures, they can contain data members, but they can also contain functions as members.
// Syntax
class class_name {
access_specifier_1:
member1;
access_specifier_2:
member2;
...
} object_names;
Working example:
// classes example
#include <iostream>
using namespace std;
class Rectangle {
int width, height;
public:
void set_values (int,int);
int area() {return width*height;}
};
void Rectangle::set_values (int x, int y) {
width = x;
height = y;
}
int main () {
Rectangle rect;
rect.set_values (3,4);
cout << "area: " << rect.area();
return 0;
}
The result is:
area: 12
For italian people: come funziona?
1. Viene per prima eseguita la funzione main ()
2. Rectangle rect; -> da qui quando scriverò rect farò riferimento a Rectangle
3. rect.set_values (3,4); -> è come se scrivessi Rectangle.set_values (3,4);
4. void Rectangle::set_values -> la classe Rectangle::funzione set_values riceve 3,4
5. quindi assegna alle variabili width = 3; height = 4;
6. tornando all’interno di main() -> rect.area(); -> la classe Rectangle, funzione area, ritorna width*height = 3*4 = 12
