"程序设计语言"版本比较

C++

   1 #include <iostream>
   2 #include <string>
   3 using namespace std;
   4 
   5 class Message {
   6 private:
   7    string txt;
   8 public:
   9    Message(string s){ txt = s;}
  10    void Print() const { cout << txt;}
  11 };
  12 
  13 int main()
  14 { 
  15    Message M("Hello world");
  16    M.Print();
  17 }

Delphi

program hellopas;
{$APPTYPE CONSOLE}
uses windows;

type Message = class
        txt : string;
        constructor create(s:string);
        procedure print;
end;

constructor Message.Create(s:string);
begin
        txt := s
end;
procedure Message.print;
begin
        writeln(txt)
end;

var m : Message;

begin
        m := Message.Create('Hello world');
        m.print()
end.

Perl

package Message;

# Message class constructor
sub new {
   my $class = shift;
   my $txt = shift;
   my $self = {};
   $self->{txt} = $txt;
   bless ($self, $class);
   return $self;
}

#Message->print() method
sub print{
   my $self = shift;
   if ($self->{txt} eq ""){
        print "No message";
   }else{
        for($i=0;$i<3;$i++){
                print $self->{txt},"\n";
        }
   }
   return $self
}

1;

require Message;

$m = Message->new("Hello World");
$m->print();

Visual BASIC

class Message
        Private theTxt
        Public Property Let TXT(S)
                theTxt = S
        End Property
        Public Sub Print()
                Wscript.echo theTxt
        End Sub
End Class

Dim M
set M = new Message 
M.TXT = "Hello world"
m.Print()

Java

class Msg{
  private String txt;
    public Msg(String s){
    txt = s;
  }
  public void print(){
    System.out.println(txt);
  }
}

public class hello{
  public static void main(String args[]){
    Msg M = new Msg("hello world");
    M.print();
    int i = 0;
  }
}