Data Types

The data types of an entity specify its associated meaning, constraints, possible values, operations, functions, and storage mode.

A variable is nothing but a name given to a storage area that our programs can manipulate. Each variable in TRObject has a specific type, which determines the size and layout of the variable's memory; the range of values that can be stored within that memory; and the set of operations that can be applied to the variable.

A type declaration is used to declare the data type of an identifier. The syntax of a type declaration is as follows:

var
  days : integer;

Integer Types

Type	Description
Byte	Values range from 0 to 255.
ShortInt	Values range from -128 to 127.
SmallInt	Values range from -32,768 to 32,767.
Integer	Values range from -2,147,483,648 to 2,147,483,647.
LongInt	Has the same range as Integer.
Int64	Values range from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.
Cardinal	Values range from 0 to 4,294,967,295.
LongWord	Values range from 0 to 4,294,967,295.
UInt64	Values range from 0 to 18,446,744,073,709,551,615.

Example

var
  age: Byte;
  temperature: ShortInt;
  year: SmallInt;
  population: Integer;
  distance: Int64;
  fileSize: Cardinal;
  largeNumber: UInt64;
  balance: LongInt;
  memorySize: LongWord;
{
  age = 25;
  temperature = -15;
  year = 1990;
  population = 1500000;
  distance = 10000000000;
  fileSize = 4000000;
  largeNumber = 1200000000000000000;
  balance = -5000000;
  memorySize = 3000000000;
  
  ShowMessage(age);
  ShowMessage(temperature);
  ShowMessage(year);
  ShowMessage(population);
  ShowMessage(distance);
  ShowMessage(fileSize);
  ShowMessage(largeNumber);
  ShowMessage(balance);
  ShowMessage(memorySize);
}

Floating-point Types

Type	Description
Single	Single precision, approximately 7-digit floating-point number.
Double	Double precision, approximately 15-digit floating-point number.
Extended	High precision, approximately 19-20 digit floating-point number.
Currency	Fixed precision (4 decimal places), suitable for financial calculations.
Real	Typically used interchangeably with Double.

Example

var
  s: Single;
  d: Double;
  e: Extended;
  c: Currency;
  r: Real;
{
  // Değişkenlere değer atayalım
  s = 1234.5678;
  d = 123456789.1234567;
  e = 1234567890123456789.123456789;
  c = 123456.7890;
  r = 987654321.1234567;

  // Sonuçları ekrana yazdıralım
  ShowMessage(s);
  ShowMessage(d);
  ShowMessage(e);
  ShowMessage(c);
  ShowMessage(r);
}

Character and String Types

Type	Description
Char	A single character (ANSI).
WideChar	A single wide character (Unicode).
String	A variable-length ANSI character string.
ShortString	A fixed-length ANSI character string up to 255 characters.
AnsiString	ANSI character string.
WideString	Unicode character string.
UnicodeString	Unicode character string, Delphi's default string type.

Example

var
  c: Char;    
  wideC: WideChar;
  s: String;    
  shortS: ShortString;  
  ansiS: AnsiString; 
  wideS: WideString;
  unicodeS: UnicodeString;

{
  c = 'A';    
  wideC = '𐍈';
  s = 'TRObject programming language'; 
  shortS = 'Hello!'; 
  ansiS = 'İstanbul';  
  wideS = 'Extended text with Unicode support: ö, ü, ş';  
  unicodeS = 'Unicode, the default string type; Turkish characters: ç, ğ, İ';


  ShowMessage('Char: '+ c);
  ShowMessage('WideChar: '+ wideC);
  ShowMessage('String: '+ s);
  ShowMessage('ShortString: '+ shortS);
  ShowMessage('AnsiString: '+ ansiS);
  ShowMessage('WideString: '+ wideS);
  ShowMessage('UnicodeString: '+ unicodeS);
}

Boolean Types

Specifies true or false logical values. This is also an integer type.

Type	Description
Boolean	Can take the values True or False.

Example

var
  b: Boolean; 

{
  b = True;      
  ShowMessage(b);
}

Date and Time Types

Type	Description
TclDateTime	Stores dates and times, represented as days and fractions of days.

Example 1

var
  currentDateTime: TclDateTime;  // TDateTime türünde bir değişken
  specificDateTime: TclDateTime;  // Belirli bir tarih ve saat için değişken

{
  currentDateTime = Now;
  specificDateTime = EncodeDate(2024, 1, 1) + EncodeTime(15, 30, 0, 0);

  ShowMessage('Current Date and Time: '+ DateTimeToStr(currentDateTime));
  ShowMessage('Specific Date and Time: '+ DateTimeToStr(specificDateTime));
}

Example 2 - Calculating the Number of Days Between Two Dates

1. Use the Trunc() function on both TclDateTime values to remove the time part and consider only the date portion.

2. The TclDateTime type is a Double:

• The integer part represents the number of days since January 1, 2014.

• The fractional part represents the time of day (e.g., hours and minutes).

3. After calculating the difference between the two dates, use the Abs() function to get the absolute value. This ensures a positive result even if the dates are entered in reverse.

4. Using this method, the number of days between two dates can be calculated easily.

var
  Difference: Integer;
  date1, date2 : TclDateTime;
{
  date1 = StrToDateTime('01.01.2024 08:30:00');
  date2 = StrToDateTime('13.05.2025 14:45:00');
  Difference = Abs(Trunc(date1) - Trunc(date2));
  ShowMessage('Difference: ' + IntToStr(Difference)); // Day difference
}

Variant Type

Type	Description
Variant	An flexible data type that can store values of different types, such as integers, floating-point numbers, strings, and booleans.

Example

var
  v: Variant;

{
  v = 42;    
  ShowMessage(v);

  v = 'Hello, World!'; 
  ShowMessage(v);
}

Array Types

Type	Description
Array	A list of a specific data type with a fixed or dynamic length. For detailed information, please refer to the Arrays page.
TclArray	A list of a specific data type with a fixed or dynamic length. For detailed information, please refer to the TclArray page.

File Types

Type	Description
TextFile	It is a data type used for processing text files. This type can be used to read or write text files line by line. For detailed information, please refer to the File Handling page.

Special Data Types

Type	Description
TclStringList	It is a useful class for storing and managing a string and provides a list-like structure. For detailed information, please refer to the TclStringList page.
TclJSONQuery	It is a class used for working with JSON data. Its usage can be found on the JSON Data Source and Cloud Database Queries pages.
TclSqliteQuery	It is a class used to interact with the SQLite database. It allows you to execute SQL queries, retrieve data, insert, update, and delete records in the SQLite database. For detailed information, please refer to the Local Database Queries page.
TclSqlQuery	It is a general class used to interact with SQL databases. This class allows you to execute SQL queries, retrieve data, insert, update, and delete records in various SQL-based database systems. For detailed information, please refer to the SQL Server Queries page.

Constants

Use of constants makes a program more readable and helps to keep special quantities at one place in the beginning of the program. TRObject allows numerical, logical, string and character constants. Constants can be declared in the declaration part of the program by specifying the const declaration.

Syntax of constant type declaration is follows:

const
  Identifier = contant_value;