Retest Solutions - Subprograms, Arrays, and File I/O

1. 

Functions

- returns a single value of a particular data type (e.g., int, real, string, boolean)

- input parameters are never modified

Procedures

- has no return value

- it is possible to modify any number of input parameters (zero, one, or more)

2.

Initializing a variable is assigning a starting value to the variable.  This is important because our programs cannot perform any operations (e.g., calculations) on a variable that is 'empty'.  In Turing, an error will occur if you try to use an uninitialized variable.

3.

var grades : array 1..30 of int

for i : 1..30

   grades(i) := 0

end for

4.

function min2(val1 : real, val2 : real) : real

   if val1 <= val2 then

      result val1

   else

      result val2

   end if

end min2

5.

procedure swapInt ( var val1, val2 : int )

   var temp : int

   temp := val1

   val1 := val2

   val2 := temp

end swapInt

6.

An include file is an additional file with code that you wish to use in your current program/file.  There are many options for the kind of information in an include file, such as definitions for records, or procedures and functions.  An include file is also useful for reducing the size of the main program file by moving some code into secondary files.

7.

var total : int := 0

var count : int := 0

for i : 2005 .. 2009

     for j : 1..8

          total := total + grades(i)(j)

          count := count + 1

     end for

end for

put "average = ", total/count

8.

var file : int

var file2 : int

var value : int

open : file, "test2009.txt", get

open : file2, "prime2009.txt", put

loop

     exit when eof(file)

     get : file, value

     if isPrime(value) then

          put : file2, value

     end if

end loop