Delphi Basics : String command

DelphiBasics

String
Type

A data type that holds a string of characters

System unit

type String;

1
2	type String[FixedSize constant];

Description

The String data type is used to hold sequences of characters, like sentences.

String is by default, actually treated as a AnsiString. It can be treated as a ShortString if the $LongStrings compiler directive is set Off (the default is On).

An AnsiChar can hold any number of characters, restricted only by memory.

Version 2 however, forces the string to be a ShortString by defining a FixedSize (up to 255 characters) of the string. This is particularly important when creating many strings, and especially so when storing strings in records (as in example 2).

Strings can be assigned from other strings, from functions that return a string, and with concatenations as in the sample code.

Notes

Strings are indexed with 1 for the first character (arrays start with 0 for the first element).

Related commands

$LongStrings		Treat string types as AnsiString or ShortString
AnsiCompareStr		Compare two strings for equality
AnsiLowerCase		Change upper case characters in a string to lower case
AnsiPos		Find the position of one string in another
AnsiString		A data type that holds a string of AnsiChars
AnsiUpperCase		Change lower case characters in a string to upper case
Concat		Concatenates one or more strings into one string
Copy		Create a copy of part of a string or an array
Delete		Delete a section of characters from a string
Length		Return the number of elements in an array or string
Move		Copy bytes of data from a source to a destination
PString		Pointer to a String value
SetLength		Changes the size of a string, or the size(s) of an array
ShortString		Defines a string of up to 255 characters
WideString		A data type that holds a string of WideChars

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Example code : Assigning to a string and then adding a bit more

var
  myString : String;
begin
  // Assign a famous sentence to this string
  myString := 'Hello World';

  // Add to this string
  myString := myString + ', how is everyone?';

  // Display the final myString value
  ShowMessage('myString = '+myString);
end;

Show full unit code

Hello World, how is everyone?

Example code : Using fixed length strings in a record

type
  // Declare a customer record
  TCustomer = Record
    firstName : String[15];
    lastName  : String[30];
  end;

var
  customer : TCustomer;

begin
  // Set up the John's customer details
  with customer do
  begin
    firstName := 'John';
    lastName  := 'Smith';
  end;

  // Now show the details of our customer
  ShowMessage('Customer name = '+customer.firstName+
                             ' '+customer.lastName);
end;

Show full unit code

Customer name = John Smith