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wtd

Wed Mar 16, 2005 5:03 pm


Syntax Quickref: Turing <--> Eiffel

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Eiffel for the Turing Programmer

Input-Output

Printing to the standard output.

Turing
put "Hello"

Eiffel 
std_output.put_string("Hello")
std_output.put_new_line

The same, without skipping to a newline.

Turing
put "Hello" ..

Eiffel
std_output.put_string("Hello")
   
Printing an integer.

Turing
put 42

Eiffel
std_output.put_integer(42)
std_output.put_new_line

Printing a floating point number.

Turing
put 42.3

Eiffel
std_output.put_real(42.3)
std_output.put_new_line

Getting a line from the keyboard.

Turing
var line : string
get line : *

Eiffel
test_proc is
  local
    line : STRING
  do
    std_input.read_line
    line := std_input.last_string
  end

Getting a single character from the keyboard.

Turing
var ch : string
get ch : 1

Eiffel
test_proc is
  local
    ch : CHARACTER
  do
    std_input.read_character
    ch := std_input.last_character
  end

Getting an integer from the keyboard.

Turing
var i : int
get i

Eiffel
test_proc is
  local
    i : INTEGER
  do
    std_input.read_integer
    i := std_input.last_integer
  end
       
Getting a float from the keyboard.

Turing
var f : real
get f

Eiffel
test_proc is
  local
    f : REAL
  do
    std_input.read_real
    f := std_input.last_real
  end
       
Math


Turing    | Eiffel       | Result
----------+--------------+---------
 4 + 3    |  4 + 3       |  7
 4 - 2    |  4 - 2       |  2
 2 * 3    |  2 * 3       |  6
 2 / 5    |  2 / 5       |  0.4
 6 div 4  |              |  1
 6 rem 4  |  6 \\ 4      |  2
 3 ** 2   |  3 ^ 2       |  9.0
 sin      |  sine        | 
 cos      |  cosine      |
          |  tangent     | 
          |  arc_sine    |
          |  arc_cosine  |
          |  arc_tangent |
 
Comparisons


Turing  | Eiffel     
--------+----------
 =      |  =      
 not=   |  /=      
 =      
 not    |  not    
 and    |  and/and then 
 or     |  or/or else

Conditional Statements/Expressions

Turing                      | Eiffel     
----------------------------+------------------------------
 if condition then          |  if condition then
   statement1               |    statement1
 elsif otherCondition then  |  elsif otherCondition then
   statement2               |    statement2
 else                       |  else
   defaultStatement         |    defaultStatement
 end if                     |  end
----------------------------+------------------------------
 case value of              |  inspect value
   label 1: statement1      |    when 1 then statement1
   label 2: statement2      |    when 2 then statement2
   label: default           |    else default
 end case                   |  end

Function Definition

Turing                              | Eiffel     
------------------------------------+--------------------------------------------
 function fooBar : string           |  foo_bar : STRING is
   result "foo, bar"                |    do 
 end fooBar                         |      Result := "foo, bar"
                                    |    end
------------------------------------+--------------------------------------------
 function square (n : int) : float  |  square(n : INTEGER) : REAL is
   result n ** 2                    |    do
 end square                         |      Result := n ^ 2
                                    |    end
------------------------------------+--------------------------------------------
 procedure greet (name : string)    |  greet(name : STRING) is
   put "Hello, " + name             |    do
 end greet                          |      std_input.put_string("Hello, " + name)
                                    |      std_input.put_new_line
                                    |    end  
------------------------------------+--------------------------------------------
 procedure greet (name : string)    |  greet(name : STRING) is
   var greeting := "Hello, " + name |    local
   put greeting                     |      greeting : STRING
 end greet                          |    do
                                    |      greeting := "Hello, " + name
                                    |      std_input.put_string("Hello, " + name)
                                    |      std_input.put_new_line
                                    |    end 
------------------------------------+--------------------------------------------
 function fact (n : int) : int      |  fact(n : INTEGER) : INTEGER is
   if n = 0 then                    |    do 
     result 1                       |      if n = 0 then
   else                             |        Result := 1
     result n * fact (n - 1)        |      else
   end if                           |        Result := n * fact(n - 1)
 end fact                           |      end
                                    |    end

Comments

Turing      | Eiffel     
------------+-------------
 %          |  --      
 /* ... */  |

More to come.