Delphi Basics : PromptForFileName command

DelphiBasics

PromptForFileName
Function

Shows a dialog allowing the user to select a file

Dialogs unit

function PromptForFileName(var FileName string; { const Filter string; const DefaultExt string; const Title string; const InitialDir string; SaveDialog Boolean = False }):Boolean;

Description

The PromptForFileName function presents a dialog to the user allowing navigation to, and selection of a file.

If the user presses OK the FileName variable is updated with the full drive/path/filename value for the selected file, and the return value is True.

If the user presses Cancel, no updates are done, and the return value is False.

The remaining parameters are all optional (although parameters used on the right mandate use of the preceding parameters) :

Filter

Used to limit the types of file displayed. The format is as follows :

'Description|filter{|...}'

For example, to show only .txt and .pas files :

Text files (*.txt)|*.txt|Delphi files (*.pas)|*.pas

DefaultExt

Used to define an extension to add to a new file name (if SaveDialog is True).

Title

Used to give a title to the dialog.

InitialDir

Positions the dialog at a given directory. For example :

'C:Program Files'

SaveDialog

Determines whether a new file can be selected for saving.

Related commands

InputBox		Display a dialog that asks for user text input, with default
InputQuery		Display a dialog that asks for user text input
ShowMessage		Display a string in a simple dialog with an OK button
ShowMessageFmt		Display formatted data in a simple dialog with an OK button
ShowMessagePos		Display a string in a simple dialog at a given screen position
TOpenDialog		Displays a file selection dialog
TSaveDialog		Displays a dialog for selecting a save file name

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Example code : Use this dialog to select a text file

var
  selectedFile   : string;

begin
  // Ask the user to select a file
  if PromptForFileName(selectedFile,
                       'Text files (*.txt)|*.txt',
                       '',
                       'Select your project file',
                       'C:\',
                       False)  // Means not a Save dialog
  then
    // Display this full file/path value
    ShowMessage('Selected file = '+selectedFile)
  else
    ShowMessage('Cancel pressed');
end;

Show full unit code

  { In the dialog, user selects C:\Files\data.txt and hits OK }

  Selected file = C:\Files\data.txt