Search

Using Dynamic Object

Dynamic objects expose members such as properties and methods at run time, instead of in at compile time. This enables you to create objects to work with structures that do not match a static type or format. For example, you can use a dynamic object to reference the HTML Document Object Model (DOM), which can contain any combination of valid HTML markup elements and attributes. Because each HTML document is unique, the members for a particular HTML document are determined at run time. A common method to reference an attribute of an HTML element is to pass the name of the attribute to the GetProperty method of the element. To reference the id attribute of the HTML element <div id="Div1">, you first obtain a reference to the <div> element, and then use divElement.GetProperty("id"). If you use a dynamic object, you can reference the id attribute as divElement.id.

Provides a base class for specifying dynamic behavior at run time. This class must be inherited from; you cannot instantiate it directly.

// The class derived from DynamicObject.
public class DynamicDictionary : DynamicObject
{
// The inner dictionary.
Dictionary<string object=""> dictionary
= new Dictionary<string object="">();
// This property returns the number of elements in the inner dictionary.
public int Count
{
get
{
return dictionary.Count;
}
}
// If you try to get a value of a property not defined in the class, this method is called.
public override bool TryGetMember(
GetMemberBinder binder, out object result)
{
// Converting the property name to lowercase so that property names become case-insensitive.
string name = binder.Name.ToLower();
// If the property name is found in a dictionary, set the result parameter to the property value and return true.Otherwise, return false.
return dictionary.TryGetValue(name, out result);
}
// If you try to set a value of a property that is not defined in the class, this method is called.
public override bool TrySetMember(
SetMemberBinder binder, object value)
{
// Converting the property name to lowercase so that property names become case-insensitive.
dictionary[binder.Name.ToLower()] = value;
// You can always add a value to a dictionary, so this method always returns true.
return true;
}
}
class Program
{
static void Main(string[] args)
{
// Creating a dynamic dictionary.
dynamic person = new DynamicDictionary();
// Adding new dynamic properties. The TrySetMember method is called.
person.FirstName = "Ellen";
person.LastName = "Adams";
// Getting values of the dynamic properties. The TryGetMember method is called. Note that property names are case-insensitive.
Console.WriteLine(person.firstname + " " + person.lastname);
// Getting the value of the Count property. The TryGetMember is not called, because the property is defined in the class.
Console.WriteLine(
"Number of dynamic properties:" + person.Count);
// The following statement throws an exception at run time.
// There is no "address" property,
// so the TryGetMember method returns false and this causes a
// RuntimeBinderException.
// Console.WriteLine(person.address);
}
}
view raw Using Dynamic Object.cs hosted with ❤ by GitHub

CGI using C++

The Common Gateway Interface (CGI) is a standard protocol for enabling applications (called CGI programs or CGI scripts) to interact with Web servers and with clients. These CGI programs can be a written in Python, PERL, Shell, C or C++ etc.

make sure that your Web Server supports CGI and it is configured to handle CGI Programs. All the CGI Programs to be executed by the HTTP server are kept in a pre-configured directory. This directory is called CGI directory and by convention it is named as /var/www/cgi-bin. By convention CGI files will have extension as .cgi, though they are C++ executable.

By default, Apache Web Server is configured to run CGI programs in /var/www/cgi-bin. 


#include <iostream>
using namespace std;
 
int main ()
{
    
   cout << "Content-type:text/html\r\n\r\n";
   cout << "<html>\n";
   cout << "<head>\n";
   cout << "<title>Hello World - First CGI Program</title>\n";
   cout << "</head>\n";
   cout << "<body>\n";
   cout << "<h2>Hello World! This is my first CGI program</h2>\n";
   cout << "</body>\n";
   cout << "</html>\n";
   
   return 0;
}


Compile above code and name the executable as cplusplus.cgi. This file is being kept in /var/www/cgi-bin directory and it has following content. Before running your CGI program make sure you have change mode of file using chmod 755 cplusplus.cgi UNIX command to make file executable.

Write then read a text file

This C# code snippet writes a text file from an internal string then reads it back using StreamReader, StreamWriter, TextReader, and TextWriter. 
using System;
using System.IO;
 
public class WriteReadClass
{
   public static void Main()
   {
      // write a text file
      TextWriter tws = new StreamWriter ("test.txt");
    
      // write the current datetime to the stream
      tws.WriteLine (DateTime.Now);
    
      // write test strings to the stream
      tws.Write (" Test string 1 to write to file.\n");
      tws.Write (" Test string 2 to write to file.\n");
    
      tws.Close();   // close the stream
 
      // now, read in the text file
      TextReader trs = new StreamReader ("test.txt");
    
      // read the first line of text 
      Console.WriteLine (trs.ReadLine());
 
      // read the rest of the text lines
      Console.WriteLine (trs.ReadToEnd());
    
      trs.Close();   // close the stream
 
      Console.Write ("\nPress \"Enter\" to exit ...");
      Console.Read();
   }
}
Subscribe to: Posts ( Atom )