Differences

This shows you the differences between two versions of the page.

--- mpl [2016/07/11 16:17] – [FOR LOOPS] gryphon
+++ mpl [2016/07/13 21:27] (current) – g00r00
@@ Line 23: / Line 23: @@
 ==== Comments ====
 All text after a two slashes (⁄⁄) is considered a comment.  It will be ignored until the next line of code.  For example:
   WriteLn ('Hello There')  ⁄⁄ This is a comment and will be ignored.
@@ Line 52: / Line 53: @@
   Const
-  UserDeleted = $04;  // established bit for userdeleted from records.pas
+    UserDeleted = $00000004;  // Deleted bit from records.pas
-                      // note: this value has changed check records.pas!
   Begin
-    GetThisUser
+    GetThisUser;
     If UserFlags AND UserDeleted <> 0 Then
       WriteLn('User is deleted');
-    End;
+  End;
 ==== Defining Variables ====
 All variables are global to all of the program, including procedures.  The syntax for declaring a variable follows:
-  Var <VarName> : <VarType>
+  Var <Variable Name> : <Variable Type>
   Examples:
-  var dummy : byte
+  Var Dummy : Byte;
-  var str   : string
+  Var Str   : String;
-  var
+  Var
-    dummy : byte,
+    Dummy1,
-    str   : string
+    Dummy2  : Byte;
 The following variable types are supported:
@@ Line 86: / Line 87: @@
   Word            Numerical      0..65535
   LongInt         Numerical      -2147483648..214748364
+  Cardinal        Numerical      0..4294967295
   Real            Numerical      9.99
-All variables except ARRAYs can be initialized when when defined.
+All variables except ARRAYs can be initialized when when defined:
   Var TotalBases : LongInt = GetMBaseTotal(False)
@@ Line 96: / Line 98: @@
 ARRAY multi-dimensional variables are supported.  The syntax for declaring an array variable is:
-  Var <VarName> :  ARRAY[<Low>..<High>] of <VarType>
+  Var <VarName> : ARRAY[<Low>..<High>] of <VarType>
-  Var <VarName> :  ARRAY[<L>..<H>, <L>..<H>] of <VarType>
+  Var <VarName> : ARRAY[<L>..<H>, <L>..<H>] of <VarType>
-  Var <VarName> :  ARRAY[<L>..<H>, <L>..<H>, <L>..<H>] of <VarType>
+  Var <VarName> : ARRAY[<L>..<H>, <L>..<H>, <L>..<H>] of <VarType>
 Examples:
-  Var Dummy : Array[1..10] of Byte
+  Var Dummy : Array[1..10] of Byte;
-  Var Str   : Array[5..10] of String
+  Var Str   : Array[5..10] of String;
-  Var Int   : Array[1..10,1..10,1..10] of Integer
+  Var Int   : Array[1..10, 1..10, 1..10] of Integer;
-HEXIDECIMAL values are supported.  They can be used in numeric variable assignment numerical evaluation, and in numeric constant variables.  A hex value must begin with a $ character.
+HEXIDECIMAL values are supported.  They can be used in numeric variable assignment numerical evaluation, and in numeric constant variables.  A hex value must begin with a $ character:
-Some examples:
   Const
     MyHexValue = $1F;
-    Value := $10;
+  Value := $10;
-  If Value = $10 Then WriteLn('Value is 16 <in decimal>');
+  If Value = $10 Then
+    WriteLn('Value is 16 <in decimal>');
 ==== Record Structures ====
@@ Line 175: / Line 177: @@
     Begin
       WriteLn (A)
-     End
+      WriteLn (A)
+    End
+==== REPEAT/UNTIL ===
+The syntax for a repeat until loop is as follows:
+  Repeat
+    <Code here>
+  Until <Boolean Expression>
+IE:
+  Repeat
+    WriteLn ('Blah blah')
+  Until A > 0 or A = 5
+==== WHILE ====
+The syntax for a while loop is as follows:
+  While <Boolean Expression> Do
+    <Code Here>
+IE:
+  While A > 0 and A = 5 Do
+    WriteLn ('Blah')
+OR:
+  While A > 0 and A = 5 Do
+    Begin
+      WriteLn ('Blah')
+      WriteLn ('More Blah')
+    End
+==== PROCEDURES ====
+The syntax for defining a procedure is as follows:
+  Procedure <Proc Name> (<varname vartype>, <varname vartype>)
+    <Code here>
+IE:
+  Procedure Hello_World
+    WriteLn ('Hello World')
+OR:
+  Procedure SomeProc (Str String, A Byte)
+    WriteLn ('Str = ' + Str)
+    WriteLn ('A   = ' + A)
+  End
+OR:
+  Procedure SomeProc (Str String)
+    Var
+      Str2 : String,
+      Str3 : String
+    Begin             <--- The keyword "BEGIN" is ignored by the compiler
+    WriteLn (Str)        just to maintain a "Pascal-like" feel.
+  End
+==== IF THEN/ELSE/END ====
+The syntax of an if/else/end statement:
+  If <boolean statement> Then
+    <True code here>
+  Else If <boolean statement> Then     (optional)
+    <True code here>
+  Else                            (optional)
+    <False code here>
+  If Not fEof(fptr) Then
+    WriteLn ('We''re not at the end of the file.')
+The above example is the same as the following example, except we've added an else statement:
+  If fEof(fptr) = False Then
+    WriteLn ('We''re not at the end of the file.')
+  Else
+    WriteLn ('This is the end of the file.')
+  If A = 1 Then
+    WriteLn ('A is 1')
+  Else If A = 2 Then
+    WriteLn ('A is 2')
+  Else If A = 5 Then
+    WriteLn ('A is 5')
+  Else
+    WriteLn ('A is not 1, 2, or 5...')
+==== CASE Statements ====
+This has actually been expanded on from the Pascal standard but still follows the same syntax.  It has been expanded to allow CASE of more variable types, such as strings.  See the included MPLTEST.MPS for examples.
+  Var I : Integer = 10
+  Case I Of
+: WriteLn('I = 1')
+: Begin
+         I:=I+1
+         WriteLn('I = 3')
+        End
+,4,5,6,7,8,9:
+      WriteLn('Not 1, 2, or 10')
+  End
+  Var S : String = 'ABCDEFG'
+    Case S[3] Of
+      'A': WriteLn('S[3] = '+S[3])
+      'B','C','D': WriteLn('S[3] = '+S[3])
+    Else
+       WriteLn('This is the default choice')
+    End
+==== FUNCTIONS ====
+The syntax for defining a function is as follows:
+  Function <Function Name> (<varname vartype>) : <result type>
+IE:
+  Function AddTen (Num Byte) : Byte
+  Begin
+    AddTen := Num + 10
+  End
+==== CONST VARIABLES ====
+The syntax for a constant variable is as follows:
+String constants:
+  Const
+    SomeStr = 'Hello World!'
+Numerical constants:
+  Const
+    SomeNum = 69
+Constant variables, like regular variables, can be separated with a comma:
+  Const
+    SomeNum = 69,
+    SomeStr = 'Hello World!'
+At the moment, constant variables cannot be used in certain places within the MPE engine.  If you are assigning a value to a variable, constant values will not be recognized.