Delphi Programming Language Cheatsheet

Delphi is a powerful and versatile programming language that has been a favorite among developers for decades. Known for its ease of use, rapid application development (RAD) capabilities, and strong support for building Windows applications, Delphi remains a popular choice for both beginners and experienced programmers. This cheatsheet serves as a quick reference guide for Delphi developers, highlighting key syntax, language features, and tips.

1. Hello World in Delphi:

program HelloWorld;

begin
  Writeln('Hello, World!');
end.

Delphi applications typically start with a program block and use the begin and end keywords to define the main body of code.

2. Variable Declaration:

var
  MyInteger: Integer;
  MyString: String;

Delphi supports various data types, and you declare variables using the var keyword.

3. Conditional Statements:

if Condition then
  // Code to execute if the condition is true
else
  // Code to execute if the condition is false

Delphi uses the if statement for conditional branching. Optionally, you can include an else block.

4. Looping Structures:

for i := 1 to 10 do
  // Code to repeat 10 times

while Condition do
  // Code to repeat while the condition is true

repeat
  // Code to repeat until the condition is true
until Condition;

Delphi supports for, while, and repeat loops for iterative operations.

5. Procedures and Functions:

procedure MyProcedure;
begin
  // Code for the procedure
end;

function MyFunction: Integer;
begin
  // Code for the function
end;

Use procedure to define a block of code without returning a value and function when a return value is expected.

6. Arrays:

var
  MyArray: array[1..5] of Integer;

Delphi allows you to declare arrays with a specified range.

7. Exception Handling:

try
  // Code that might raise an exception
except
  // Code to handle the exception
end;

Use try and except blocks for exception handling.

8. Classes and Objects:

type
  MyClass = class
    // Class members and methods
  end;

var
  MyObject: MyClass;
begin
  MyObject := MyClass.Create;
  // Code using the object
  MyObject.Free;
end.

Delphi is an object-oriented language, and classes are a fundamental part of its structure.

9. File Handling:

var
  MyFile: TextFile;
begin
  AssignFile(MyFile, 'myfile.txt');
  Reset(MyFile); // or Rewrite(MyFile) to create a new file
  // Code to read or write to the file
  CloseFile(MyFile);
end.

Delphi provides simple file handling procedures with AssignFile, Reset, Rewrite, and CloseFile.

10. GUI Development:

Delphi is well-known for its RAD capabilities, especially in building graphical user interfaces (GUI). Components like TButton, TEdit, and TForm make it easy to design interactive applications.

This cheatsheet provides a quick glimpse into the syntax and features of Delphi. For more in-depth learning, refer to the official documentation and explore the extensive range of libraries and components available for Delphi development.