Android App Development Tutorial

This tutorial is meant to target devlopers who have little or no experience in Android or C# development. If you are brand new in programming you will probably be able to follow but you will gain a lot from reading up on basic programming concepts such as classes, objects, class inheritance and events. If you are experienced you will know what parts to skip :-) To get started with programming for the Android platform we are going to make a...

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Pascal Programming Lesson #14 - Linked Lists

A linked list is like an array except that the amount of elements in a linked list can change unlike an array. A linked list uses pointers to point to the next or previous element. Single linked lists There are 2 types of single linked lists which are called queues and stacks. Queues A queue is like standing in a queue at a shop. The first person that joins a queue is the first person to be served. You must always join at the back of a queue because if you join at the front the other people will be angry. This is called FIFO(First In First...

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Pascal Programming Lesson #13 - Pointers

A pointer is a type of variable that stores a memory address. Because it stores a memory address it is said to be pointing to it. There are 2 types of pointers which are typed and untyped. A typed pointer points to a variable such as an integer. An untyped pointer can point to any type of variable. Declaring and using typed pointers When you declare a typed pointer you must put a ^ in front of the variable type which you want it to point to. Here is an example of how to declare a pointer to an integer: program Pointers;var   p:...

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Pascal Programming Lesson #12 - Units

We already know that units, such as the crt unit, let you use more procedures and functions than the built-in ones. You can make your own units which have procedures and functions that you have made in them. To make a unit you need to create new Pascal file which we will call MyUnit.pas. The first line of the file should start with the unit keyword followed by the unit's name. The unit's name and the unit's file name must be exactly the same. unit MyUnit; The next line is the interface keyword. After this you must put the names...

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Pascal Programming Lesson #11 - Data Files

Data files are different from text files in a few ways. Data files are random access which means you don't have to read through them line after line but instead access any part of the file at any time. Here is how you declare a data file: program DataFiles;var   f: file of Byte;beginend. We then use Assign in the same way as we do with a text file. program DataFiles;var   f: file of Byte;begin   Assign(f,'MyFile.dat');end. You can use Rewrite to create a new file or overwrite...

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Pascal Programming Lesson #10 - Text Files

You should by now know that a text file is a file with lines of text. When you want to access a file in Pascal you have to first create a file variable. program Files;var   f: Text;beginend. After the variable has been declared you must assign the file name to it. program Files;var   f: Text;begin   Assign(f,'MyFile.txt');end. To create a new empty file we use the Rewrite command. This will overwrite any files that exist with the same name. program Files;var   f:...

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Pascal Programming Lesson #9 - Procedures and Functions

Procedures Procedures are sub-programs that can be called from the main part of the program. Procedures are declared outside of the main program body using the procedure keyword. Procedures must also be given a unique name. Procedures have their own begin and end. Here is an example of how to make a procedure called Hello that prints "Hello" on the screen. program Procedures;procedure Hello;begin   Writeln('Hello');end;beginend. To use a procedure we must call it by using its name in the main body. program...

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Pascal Programming Lesson #8 - Types, Records and Sets

Types It is possible to create your own variable types using the type statement. The first type you can make is records. Records are 2 or more variables of different types in one. An example of how this could be used is for a student who has a student number and a name. Here is how you create a type: program Types;Type   Student = Record      Number: Integer;      Name: String;   end;beginend. After you have created the type you must declare...

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Pascal Programming Lesson #7 - Arrays

Arrays are variables that are made up of many variables of the same data type but have only one name. Here is a visual representation of an array with 5 elements: 1value 1 2value 2 3value 3 4value 4 5value 5 Arrays are declared in almost the same way as normal variables are declared except that you have to say how many elements you want in the array. program Arrays;var   a: array[1..5] of Integer;beginend. We access each of the elements using the number of the elements behind it in square brackets. program Arrays;var   a:...

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