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| -rw-r--r-- | pascal.html.markdown | 86 |
1 files changed, 77 insertions, 9 deletions
diff --git a/pascal.html.markdown b/pascal.html.markdown index 4144f900..28dcc10f 100644 --- a/pascal.html.markdown +++ b/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. ``` + |