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TStringList is a utility class type. It is extremely useful for many kinds of list processing. Items in a string list may be inserted, moved and sorted.
The list can be built string by string, or loaded from a comma separated big string, or even from a text file. TStringList is derived from TStrings. Whilst you can use TStrings, it is not recommended since it is incomplete - some of the methods are abstract. TStringList implements these abstract methods (Clear, Delete and Insert). We'll cover the main properties and methods of TStringList, including those derived from TStrings Count property Returns the number of strings in the list Capacity property Set or get the current capacity of the string list. You would manage this capacity for performance reasons. Strings property Get or update the string at a given index in the list (the first list item has index 0). Note that the Strings property is the default property. This means that you can use it without specifying its name: myName := names.Strings[4]; is equivalent to : myName := names[4]; Text property Set or get the list via a big string. This string will have each string terminated with a carriage return and line feed combination (CRLF). Useful for loading from a visual object that can hold multiple lines of text. CommaText property Get or set the list via a big string. This string will have the list strings separated by commas. This is useful for loading from a text spreadsheet export. When getting, if a string contains embedded spaces, it will be enclosed in double quote marks. DelimitedText property Get or set the list via a big string. This string will have the list strings separated by the Delimiter value (default is a comma). Strings containing embedded blanks must be enclosed in the QuoteChar (default is "). QuoteChar property Used to enclose strings that have embedded blanks when using DelimitedText. Delimiter property Used to separate strings when using DelimitedText. Names property Strings in a string list can be treated as name/value pairs, as in the second code example. Each string must have no embedded blanks, and contain an embedded = sign (or whatever the current NameValueSeparator variable is). This is a very useful concept. See the Value and ValueFromIndex properties, and the IndexOfName method. Values property Returns the value for a given name when using name/value pair strings (see above). ValueFromIndex property Returns the value by string index (starting at 0) when using name/value pairs. CaseSensitive property When true, Delphi treats strings as mixed case when perforing certain operations, such as Sort. Duplicates property This property may have one of the following TDuplicates enumeration values:
You should of course set this property to the desired value before adding strings. Sorted property When true all strings added will into a sorted sequence. When false, they are added at the end. See also the Sort method. Objects property Returns the object associated with the string at the given index, if present. Add method Will add the given string to the list, returning its allocated index position (starting with 0). Append method As Add but does not return the index value. Insert method Inserts a string at the given index position. Position 0 will force an insert at the start. Delete method Deletes the string at the given index. Clear method Deletes all strings from the list. Move method Moves a string from one index position to another, shifting other strings around as appropriate. Exchange method Swaps two strings in the list, as identified by their index positions. IndexOf method Gets the index position of the first string matching the given string. Or -1 if not found. IndexOfName method Gets the index position of the first name/value pair string where the name matches the given string. Or -1 if not found. Find method Same as IndexOf but used with sorted string lists. Sort method When Sorted is false, this will force a sort of the list. AddStrings method Adds the strings from another list into this one. Assign method Replaces the current list with the contents of another list. LoadFromFile method Very useful indeed - loads a string list from a text file. Each text line (as terminated by CRLF - see DelimitedText) becomes a list string. SaveToFile method Will save a string list to a text file. | ||||||||||||
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| Example code : A simple example |
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animals : TStringList; // Define our string list variable i : Integer; begin // Define a string list object, and point our variable at it animals := TStringList.Create; // Now add some names to our list animals.Add('Cat'); animals.Add('Mouse'); animals.Add('Giraffe'); // Now display these animals for i := 0 to animals.Count-1 do ShowMessage(animals[i]); // animals[i] equates to animals.Strings[i] // Free up the list object animals.Free; end; |
| Show full unit code |
| Cat
Mouse Giraffe |
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