Program to illustrate 'typedef' keyword

#include <iostream>
using std::cout;
using std::endl;

typedef float FLOAT32;
typedef double FLOAT64;     //By using typedef Keyword we can make alias of datatypes
typedef unsigned int U32;    //it is something like macro

int main()
{
    U32 bigint = 23433;
    FLOAT32 myFloat = 6.6;
    FLOAT64 myDouble = 34343.3;
   
    cout << "  bigint: " << bigint;
    cout << "\n myFloat: " << myFloat;
    cout << "\nmyDouble: " << myDouble;
}

what is typedef:
typedef is a keyword in the C and C++ programming languages. The purpose
of typedef is to assign alternative names to existing types

what is the use of typedef keyword:
1) it provides a means to make a program more portable. Instead of having to
    change a type everywhere it appears throughout the program's source 
    files, only a single typedef statement needs to be changed.
2) A typedef can make a complex declaration easier to understand. 

By using typedef Keyword we can make alias of datatypes

Program to illustrate 'const' keyword

The const keyword is used to modify a declaration of a field or local variable. It specifies that the value of the field or the local variable cannot be modified.

// program to illustrate const keyword
// using  c#

using System;

public class ConstTest
{
    class MyClass
    {
        public int x;
        public int y;
        public const int c1 = 5;
        public const int c2 = c1 + 5;
       
        public  MyClass(int p1, int p2)
        {
            x = p1;
            y = p2;
        }
    }
   
    public static void Main()
    {
        MyClass mC = new MyClass(11, 22);
        Console.WriteLine ("x = {0}, y = {1}", mC.x, mC.y);
        Console.WriteLine ("c1 = {0}, c2 = {1}", MyClass.c1, MyClass.c2);
    }
}

OUTPUT:
x = 11, y = 22
c1 = 5, c2 = 10

The list of 'keyword' you must known

1. friend -- Grant non-member function access to private data.
2. inline -- Optimize calls to short functions.
3. namespace -- Partition the global namespace by defining a scope.
4. new -- Allocate dynamic memory for a new variable.
5. static -- Create permanent storage of a variable.
6. template -- Create generics functions.
7. this -- A pointer to the current object.
8. using -- Import complete or partial namespace.
9. virtual -- Create a function that can be overridden by a derived class.