[pascal/en] add additional data types and arrays

This commit is contained in:
Keith Miyake 2018-10-04 12:18:50 -07:00
parent e867dfd7b6
commit 29422fb84d

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@ -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
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;
@ -76,7 +134,7 @@ 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
@ -85,10 +143,19 @@ Begin
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.
```