[pascal/en] add additional data types and arrays

pascal.html.markdown

@@ -25,6 +25,10 @@ to compile and run a pascal program you could use a free pascal compiler. [Downl
 //name of the program
 program learn_pascal; //<-- dont forget a semicolon
 
+const
+    {
+        this is where you should declare constant values
+    }
 type
     {
         this is where you should delcare a custom
@@ -55,17 +59,71 @@ var
 //or this
 var a,b : integer;
 ```
+
 ```pascal
 program Learn_More;
 //Lets learn about data types and their operations
 
+const
+    PI = 3.141592654;
+    GNU = 'GNU's Not Unix';
+        // constants are conventionally named using CAPS
+        // their values are fixed and cannot be changed during runtime
+        // holds any standard data type (integer, real, boolean, char, string)
+
+type
+    ch_array : array [0..255] of char;
+        // arrays are new 'types' specifying the length and data type
+        // this defines a new data type that contains 255 characters
+        // (this is functionally equivalent to a string[256] variable)
+    md_array : array of array of integer;
+        // nested arrays are equivalent to multidimensional arrays
+        // can define zero (0) length arrays that are dynamically sized
+        // this is a 2-dimensional array of integers
+
 //Declaring variables
-var 
-    int : integer; // a variable that contains an integer number data types
-    ch  : char;    // a variable that contains a character data types
-    str : string; // a variable that contains a string data types
-    r   : real;   // a variable that contains a real number data types
-    bool : boolean; //a variables that contains a Boolean(True/False) value data types
+var
+    int, c, d  : integer;
+           // three variables that contain integer numbers
+           // integers are 16-bits and limited to the range [-32,768..32,767]
+    r    : real;
+           // a variable that contains a real number data types
+           // reals can range between [3.4E-38..3.4E38]
+    bool : boolean;
+           // a variable that contains a Boolean(True/False) value
+    ch   : char;
+           // a variable that contains a character value
+           // char variables are stored as 8-bit data types so no UTF
+    str  : string;
+           // a non-standard variable that contains a string value
+           // strings are an extension included in most Pascal compilers
+           // they are stored as an array of char with default length of 255.
+    s    : string[50];
+           // a string with maximum length of 50 chars.
+           // you can specify the length of the string to minimize memory usage
+    my_str: ch_array;
+           // you can declare variables of custom types
+    my_2d : md_array;
+           // dynamically sized arrays need to be sized before they can be used.
+
+    // additional integer data types
+    b    : byte;     // range [0..255]
+    shi  : shortint; // range [-128..127]
+    smi  : smallint; // range [-32,768..32,767] (standard Integer)
+    w    : word;     // range [0..65,535]
+    li   : longint;  // range [-2,147,483,648..2,147,483,647]
+    lw   : longword; // range [0..4,294,967,295]
+    c    : cardinal; // longword
+    i64  : int64;    // range [-9223372036854775808..9223372036854775807]
+    qw   : qword;    // range [0..18,446,744,073,709,551,615]
+
+    // additional real types
+    rr   : real;     // range depends on platform (i.e., 8-bit, 16-bit, etc.)
+    rs   : single;   // range [1.5E-45..3.4E38]
+    rd   : double;   // range [5.0E-324 .. 1.7E308]
+    re   : extended; // range [1.9E-4932..1.1E4932]
+    rc   : comp;     // range [-2E64+1 .. 2E63-1]
+
 Begin
     int := 1;// how to assign a value to a variable
     r   := 3.14;
@@ -76,19 +134,28 @@ Begin
     //arithmethic operation
     int := 1 + 1; // int = 2 overwriting the previous assignment
     int := int + 1; // int = 2 + 1 = 3;
-    int := 4 div 2; //int = 2 a division operation which the result will be floored
+    int := 4 div 2; //int = 2 division operation where result will be floored
     int := 3 div 2; //int = 1
     int := 1 div 2; //int = 0
 
     bool := true or false; // bool = true
     bool := false and true; // bool = false
     bool := true xor true; // bool = false
-    
+
     r := 3 / 2; // a division operator for real
-    r := int; // you can assign an integer to a real variable but not the otherwise
+    r := int; // can assign an integer to a real variable but not the reverse
 
     c := str[1]; // assign the first letter of str to c
     str := 'hello' + 'world'; //combining strings
+
+    my_str[0] := 'a'; // array assignment needs an index
+
+    setlength(my_2d,10,10); // initialize dynamically sized arrays: 10×10 array
+    for c := 0 to 9 do // arrays begin at 0 and end at length-1
+        for d := 0 to 9 do // for loop counters need to be declared variables
+        my_2d[c,d] := c * d;
+          // address multidimensional arrays with a single set of brackets
+
 End.
 ```
 
@@ -136,3 +203,4 @@ Begin // main program block
 End.
 
 ```
+