Hello World — By different types of programmers

High School / Junior High

10 PRINT "HELLO WORLD"
20 END

First Year in College

program Hello(input, output)
 begin
    writeln('Hello World')
 end.

Senior Year in College

(defun hello
 (print
  (cons 'Hello (list 'World))))

New professional

#include
void main(void)
 {
  char *message[] = {"Hello ", "World"};
   int i;

   for(i = 0; i < 2; ++i)
     printf("%s", message[i]);
   printf("\n");
}

Seasoned professional

#include 
#include  
 class string
{
 private:
  int size;
   char *ptr;
 public:
   string() : size(0), ptr(new char('\0')) {}
   string(const string &s) : size(s.size)
  {
   ptr = new char[size + 1];
   strcpy(ptr, s.ptr);
   }
   ~string()
  {
   delete [] ptr;
   }
   friend ostream &operator  <<(ostream &, const string &);
   string &operator=(const char *);
  };
 ostream &operator <<(ostream &stream, const string &s)
 {
   return(stream  << s.ptr);
 }
 string &string::operator=(const char *chrs)
 {
  if (this != &chrs)
   {
    delete [] ptr;
  size = strlen(chrs);
  ptr = new char[size + 1];
     strcpy(ptr, chrs);
  }
   return(*this);
}
 int main()
 {
   string str;
   str = "Hello World";
   cout  << str  << endl;
   return(0);
 }

Apprentice Hacker

#!/usr/local/bin/perl
$msg="Hello, world.\n";
if ($#ARGV >= 0) {
  while(defined($arg=shift(@ARGV))) {
    $outfilename = $arg;
    open(FILE, ">" . $outfilename) || die "Can't write $arg: $!\n";
    print (FILE $msg);
    close(FILE) || die "Can't close $arg: $!\n";
  }
} 
else {
 print ($msg);
}
1;

Experienced Hacker

#include 
#define S "Hello, World\n"
main(){exit(printf(S) == strlen(S) ? 0 : 1);}

Seasoned Hacker

% cc -o a.out ~/src/misc/hw/hw.c
% a.out

Guru Hacker

% cat
Hello, world.
^D