2016-02-09 Beginners guide to Arexx

2016-02-09 beginners-guide-to-arexx

# Title: Beginners guide to Arexx
# Author: Mikael Lundin
# Link: http://blog.mikaellundin.name/2016/02/09/beginners-guide-to-arexx.html

BubbleSort.rexx

/* Sorting a list of random numbers with bubble sort */
SAY "How many numbers should we sort? (number)"
PULL max

/* Randomize numbers */
DO i = 1 to max
  numbers.i = RANDOM(1, 100)
END

SAY "Random numbers"
CALL print

CALL sort

SAY "Sorted numbers"
CALL print

exit

swap: procedure expose numbers.
  ARG i, j
  swap = numbers.i
  numbers.i = numbers.j
  numbers.j = swap
return

sort: procedure expose max numbers.
  DO i = 1 to (max - 1)
    DO j = (i + 1) to max
      IF numbers.i > numbers.j THEN CALL swap(i, j)
    END j
  END i
return

print: procedure expose max numbers.
  output = ""
  DO i = 1 to max
    output = output || numbers.i || ", "
  END i
  SAY output
return

Cipher.rexx

/* A small program to encrypt a string with ceasar cipher */
alphabet = 25
ascii = C2D("A")

SAY "Enter the encryption key (number):"
PULL encKey

SAY "Enter the phrase to encrypt (capital letters):"
PULL data

result = ""
DO i = 1 to LENGTH(data)
  char = C2D(LEFT(data, 1)) - ascii
  encChar = D2C(((char + encKey) // alphabet) + ascii)
  result = result + encChar
  data = RIGHT(data, LENGTH(data) - 1)
END i

SAY "Encrypted phrase:" result

Communication.rexx

/* This is a program to demonstrate inter process communication */
DO FOREVER
  SAY "Please select of the following"
  SAY "  1) Send message to open instances"
  SAY "  2) Retrieve message"
  SAY "  Q) Quit"
  PULL selection

  SELECT
    WHEN selection = 1 THEN CALL sendmessage
    WHEN selection = 2 THEN CALL retrievemessage
    WHEN selection = "Q" THEN LEAVE
    OTHERWISE NOP
  END
END
EXIT

sendmessage: procedure
  SAY "Type in the message you want to send"
  PULL message
  SETCLIP("message", message)
return

retrievemessage: procedure
  SAY "Pulling message from external source"
  message = GETCLIP("message")
  SAY message
return

Factorial.rexx

/* Calculate the factorial of a number */
SAY "Calculate the factorial of: "
PULL n

result = 1
DO i = n to 1 by -1
  result = result * i
END

SAY n || "! =" result

Fibonacci.rexx

/* Get a list of fibonacci numbers */
SAY "How long fibonacci sequence do you want? (number)"
PULL size

fibonacci.1 = 1
fibonacci.2 = 2

DO i = 3 to size
  prev = i - 1
  prevprev = prev - 1
  fibonacci.i = fibonacci.prevprev + fibonacci.prev
END

SAY "Fibonacci"

DO i = 1 to size
  SAY i || ":" fibonacci.i
END

Find.rexx

/* Find an element in an array */
numbers = ""

/* Create vector */
vector.1 = 12
vector.2 = 23
vector.3 = 34
vector.4 = 45
vector.5 = 56

SAY "Numbers: 12 23 34 45 56"
SAY "Test if number is in vector:"
PULL guess

IF find(1, 5, guess, vector) THEN SAY "Yes, number exists"
ELSE SAY "No, number doesn't exist"

exit

find:
  ARG min, max, search, vector

  /* found/*
  IF search = vector.min | search = vector.max THEN return 1

  /* not found */
  ELSE IF max - min < 2 THEN return 0

  /* keep looking */
  ELSE
    DO
      middle = min + TRUNC((max - min) / 2)
      IF search >= vector.middle THEN
        return find(middle, max, search, vector)
      ELSE
        return find(min, middle - 1, search, vector)
    END

  SAY "Error in find function"
  EXIT
return

GuessTheNumber.rexx

/* This is a small game that lets you guess a random number */
number = RANDOM(1, 1000)
guess = -1
guesses = 0

SAY "The number is between 1-1000."

DO while guess ~= number
  SAY "Guess the number: "
  PULL guess

  IF guess > number THEN SAY "Your guess was too high"
  ELSE SAY "Your guess was too low"

  guesses = guesses + 1
END

SAY "You've found the in" guesses "tries"."

HelloWorld.rexx

/* Prints Hello World! */
SAY "Hello World!"

Procedures.rexx

/* This program will demonstrate procedures */
width = 33

call separator
call title
call separator
exit

title:
SAY "*** AREXX WILL RULE THE WORLD ***"
return

separator:
SAY COPIES("*", width)
return

Pyramid.rexx

/* This program will print a pyramid of a hiehgt the user specify */
SAY "Height of the pyramid:"
PULL height

DO i=1 to height
  spaces = ""
  stars = ""

  DO j=1 to (height - i)
    spaces = spaces || " "
  END

  DO j=1 to (i + i - 1)
    stars = stars || "*"
  END

  SAY spaces || stars
END

Types.rexx

/* This is a type test */
seven = "7"
reallySeven = 7
almostSeven = 7.0000000001

SAY '22'x seven '22'x "=" reallySeven ":" (seven = reallySeven)
SAY '22'x seven '22'x "==" reallySeven ":" (seven == reallySeven)
SAY '22'x seven '22'x "=" almostSeven ":" (seven = almostSeven)
SAY '22'x seven '22'x "==" almostSeven ":" (seven == almostSeven)
SAY '22'x reallySeven '22'x "=" almostSeven ":" (reallySeven = almostSeven)
SAY '22'x reallySeven '22'x "==" almostSeven ":" (reallySeven == almostSeven)

Variables.rexx

/* This program asks the user for name and shoe size */
SAY "What is your name?"
PULL name
SAY "What is your shoe size?"
PULL size

SAY "Hello" name "your shoe size is" size