QLineEdit Class

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# QLineEdit Class Reference

The QLineEdit widget is a one-line text editor. More...

`#include <qlineedit.h>`

Inherits QFrame.

List of all member functions.

## Public Members

- QLineEdit ( QWidget * parent, const char * name = 0 )
- QLineEdit ( const QString & contents, QWidget * parent, const char * name = 0 )
- ~QLineEdit ()
- QString text () const
- QString displayText () const
- int maxLength () const
- bool frame () const
- enum EchoMode { Normal, NoEcho, Password }
- EchoMode echoMode () const
- bool isReadOnly () const
- const QValidator * validator () const
- virtual QSize sizeHint () const
- virtual QSize minimumSizeHint () const
- int cursorPosition () const
- bool validateAndSet ( const QString & newText, int newPos, int newMarkAnchor, int newMarkDrag )
- int alignment () const
- void cursorLeft ( bool mark, int steps = 1 ) (obsolete)
- void cursorRight ( bool mark, int steps = 1 ) (obsolete)
- void cursorForward ( bool mark, int steps = 1 )
- void cursorBackward ( bool mark, int steps = 1 )
- void cursorWordForward ( bool mark )
- void cursorWordBackward ( bool mark )
- void backspace ()
- void del ()
- void home ( bool mark )
- void end ( bool mark )
- void setEdited ( bool )
- bool edited () const
- bool hasSelectedText () const
- QString selectedText () const
- bool getSelection ( int * start, int * end )
- bool isUndoAvailable () const
- bool isRedoAvailable () const
- bool hasMarkedText () const (obsolete)
- QString markedText () const (obsolete)
- void setPasswordChar ( QChar c )
- QChar passwordChar () const
- bool dragEnabled () const
- int characterAt ( int xpos, QChar * chr ) const

## Public Slots

- virtual void setText ( const QString & )
- virtual void selectAll ()
- virtual void deselect ()
- virtual void clearValidator ()
- virtual void insert ( const QString & newText )
- virtual void clear ()
- virtual void undo ()
- virtual void redo ()
- virtual void setMaxLength ( int )
- virtual void setFrame ( bool )
- virtual void setEchoMode ( EchoMode )
- virtual void setReadOnly ( bool )
- virtual void setValidator ( const QValidator * v )
- virtual void setSelection ( int start, int length )
- virtual void setCursorPosition ( int )
- virtual void setAlignment ( int flag )
- virtual void cut ()
- virtual void copy () const
- virtual void paste ()
- virtual void setDragEnabled ( bool b )

## Signals

- void textChanged ( const QString & )
- void returnPressed ()
- void selectionChanged ()

## Properties

- Alignment alignment - the alignment of the line edit
- int cursorPosition - the current cursor position for this line edit
- QString displayText - the text that is displayed (read only)
- bool dragEnabled - whether the lineedit starts a drag if the user presses and moves the mouse on some selected text
- EchoMode echoMode - the echo mode of the line edit
- bool edited - the edited flag of the line edit
- bool frame - whether the line edit draws itself with a frame
- bool hasMarkedText - whether part of the text has been selected by the user (e.g. by clicking and dragging) (read only) (obsolete)
- bool hasSelectedText - whether there is any text selected (read only)
- QString markedText - the text selected by the user (e.g. by clicking and dragging), or QString::null if no text is selected (read only) (obsolete)
- int maxLength - the maximum permitted length of the text in the editor
- bool readOnly - whether the line edit is read only
- bool redoAvailable - whether redo is available (read only)
- QString selectedText - any text selected by the user or QString::null (read only)
- QString text - the text in the line
- bool undoAvailable - whether undo is available (read only)

## Protected Members

- virtual void keyPressEvent ( QKeyEvent * e )
- void repaintArea ( int from, int to ) (obsolete)
- virtual QPopupMenu * createPopupMenu ()

## Detailed Description

The QLineEdit widget is a one-line text editor.

A line edit allows the user to enter and edit a single line of plain text with a useful collection of editing functions, including undo and redo, cut and paste, and drag and drop.

By changing the echoMode() of a line edit, it can also be used as a "write-only" field, for inputs such as passwords.

The length of the field can be constrained to maxLength(), or the value can be arbitrarily constrained by setting a validator().

A closely related class is QTextEdit which allows multi-line, rich-text editing.

You can change the text with setText() or insert(). The text is retrieved with text(); the displayed text (which may be different, see EchoMode) is retrieved with displayText(). Text can be selected with setSelection() or selectAll(), and the selection can be cut(), copy()ied and paste()d. The text can be aligned with setAlignment().

When the text changes the textChanged() signal is emitted; when the Return or Enter key is pressed the returnPressed() signal is emitted.

By default, QLineEdits have a frame as specified by the Windows and Motif style guides; you can turn it off by calling setFrame(FALSE).

The default key bindings are described below. A right mouse button menu presents some of the editing commands to the user.

- Left Arrow - moves the cursor one character to the left.
- Right Arrow - moves the cursor one character to the right.
- Backspace - deletes the character to the left of the cursor.
- Home - moves the cursor to the beginning of the line.
- End - moves the cursor to the end of the line.
- Delete - deletes the character to the right of the cursor.
- Shift+Left Arrow - moves and selects text one character to the left.
- Shift+Right Arrow - moves and selects text one character to the right.
- Ctrl+A - moves the cursor to the beginning of the line.
- Ctrl+B - moves the cursor one character to the left.
- Ctrl+C - copies the selected text to the clipboard. (Windows also supports Ctrl+Insert for this operation.)
- Ctrl+D - deletes the character to the right of the cursor.
- Ctrl+E - moves the cursor to the end of the line.
- Ctrl+F - moves the cursor one character to the right.
- Ctrl+H - deletes the character to the left of the cursor.
- Ctrl+K - deletes to the end of the line.
- Ctrl+V - pastes the clipboard text into line edit. (Windows also supports Shift+Insert for this operation.)
- Ctrl+X - deletes the selected text and copies it to the clipboard. (Windows also supports Shift+Delete for this operation.)
- Ctrl+Z - undoes the last operation.
- Ctrl+Y - redoes the last undone operation.

Any other key sequence, that represents a valid character, will cause the character to be inserted into the line.

See also QTextEdit, QLabel, QComboBox, GUI Design Handbook: Field, Entry and Basic Widgets.

## Member Type Documentation

### QLineEdit::EchoMode

This enum type describes how a line edit should display its contents. The defined values are:

- `QLineEdit::Normal` - display characters as they are entered. This is the default.
- `QLineEdit::NoEcho` - do not display anything. This may be appropriate for passwords where even the length of the password should be kept secret.
- `QLineEdit::Password` - display asterisks instead of the characters actually entered.

See also echoMode and echoMode.

## Member Function Documentation

### QLineEdit::QLineEdit ( QWidget * parent, const char * name = 0 )

Constructs a line edit with no text.

The maximum text length is set to 32767 characters.

The parent and name arguments are sent to the QWidget constructor.

See also text and maxLength.

### QLineEdit::QLineEdit ( const QString & contents, QWidget * parent, const char * name = 0 )

Constructs a line edit containing the text contents.

The cursor position is set to the end of the line and the maximum text length to 32767 characters.

The parent and name arguments are sent to the QWidget constructor.

See also text and maxLength.

### QLineEdit::~QLineEdit ()

Destroys the line edit.

### int QLineEdit::alignment () const

Returns the alignment of the line edit. See the "alignment" property for details.

### void QLineEdit::backspace ()

Deletes the character to the left of the text cursor and moves the cursor one position to the left. If any text has been selected by the user (e.g. by clicking and dragging), the cursor will be put at the beginning of the selected text and the selected text will be removed.

See also del().

### int QLineEdit::characterAt ( int xpos, QChar * chr ) const

Returns the index position of the character which is at xpos (in logical coordinates from the left). If chr is not 0, `*<em>chr</em>` is populated with the character at this position.

### void QLineEdit::clear ()`[virtual slot]`

Clears the contents of the editor. This is equivalent to setText("").

### void QLineEdit::clearValidator ()`[virtual slot]`

This slot is equivalent to setValidator( 0 ).

### void QLineEdit::copy () const`[virtual slot]`

Copies the selected text to the clipboard, if there is any, and if echoMode() is Normal.

See also cut() and paste().

### QPopupMenu * QLineEdit::createPopupMenu ()`[virtual protected]`

This function is called to create the popup menu which is shown when the user clicks on the lineedit with the right mouse button. If you want to create a custom popup menu, reimplement this function and return the popup menu you create. The popup menu's ownership is transferred to the caller.

### void QLineEdit::cursorBackward ( bool mark, int steps = 1 )

Moves the cursor back steps characters. If mark is TRUE each character moved over is added to the selection; if mark is FALSE the selection is cleared.

See also cursorForward().

### void QLineEdit::cursorForward ( bool mark, int steps = 1 )

Moves the cursor forward steps characters. If mark is TRUE each character moved over is added to the selection; if mark is FALSE the selection is cleared.

See also cursorBackward().

### void QLineEdit::cursorLeft ( bool mark, int steps = 1 )

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

For compatibilty with older applications only. Use cursorBackward() instead.

See also cursorBackward().

### int QLineEdit::cursorPosition () const

Returns the current cursor position for this line edit. See the "cursorPosition" property for details.

### void QLineEdit::cursorRight ( bool mark, int steps = 1 )

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

Use cursorForward() instead.

See also cursorForward().

### void QLineEdit::cursorWordBackward ( bool mark )

Moves the cursor one word backward. If mark is TRUE, the word is also selected.

See also cursorWordForward().

### void QLineEdit::cursorWordForward ( bool mark )

Moves the cursor one word forward. If mark is TRUE, the word is also selected.

See also cursorWordBackward().

### void QLineEdit::cut ()`[virtual slot]`

Copies the selected text to the clipboard and deletes it, if there is any, and if echoMode() is Normal.

If the current validator disallows deleting the selected text, cut() will copy it but not delete it.

See also copy() and paste().

### void QLineEdit::del ()

Deletes the character on the right side of the text cursor. If any text has been selected by the user (e.g. by clicking and dragging), the cursor will be put at the beginning of the selected text and the selected text will be removed.

See also backspace().

### void QLineEdit::deselect ()`[virtual slot]`

De-selects all text (i.e. removes highlighting) and leaves the cursor at the current position.

See also setSelection() and selectAll().

### QString QLineEdit::displayText () const

Returns the text that is displayed. See the "displayText" property for details.

### bool QLineEdit::dragEnabled () const

Returns TRUE if the lineedit starts a drag if the user presses and moves the mouse on some selected text; otherwise returns FALSE. See the "dragEnabled" property for details.

### EchoMode QLineEdit::echoMode () const

Returns the echo mode of the line edit. See the "echoMode" property for details.

### bool QLineEdit::edited () const

Returns the edited flag of the line edit. See the "edited" property for details.

### void QLineEdit::end ( bool mark )

Moves the text cursor to the end of the line. If mark is TRUE, text is selected towards the last position; otherwise, any selected text is unselected if the cursor is moved.

See also home().

### bool QLineEdit::frame () const

Returns TRUE if the line edit draws itself with a frame; otherwise returns FALSE. See the "frame" property for details.

### bool QLineEdit::getSelection ( int * start, int * end )

This function sets `*<em>start</em>` to the position in the text where the selection starts and `*<em>end</em>` to the position where the selection ends. Returns TRUE if start and end are not null and if there is some selected text; otherwise returns FALSE.

See also setSelection().

### bool QLineEdit::hasMarkedText () const

Returns TRUE if part of the text has been selected by the user (e.g. by clicking and dragging); otherwise returns FALSE. See the "hasMarkedText" property for details.

### bool QLineEdit::hasSelectedText () const

Returns TRUE if there is any text selected; otherwise returns FALSE. See the "hasSelectedText" property for details.

### void QLineEdit::home ( bool mark )

Moves the text cursor to the beginning of the line. If mark is TRUE, text is selected towards the first position; otherwise, any selected text is unselected if the cursor is moved.

See also end().

### void QLineEdit::insert ( const QString & newText )`[virtual slot]`

Removes any selected text, inserts newText, and validates the result. If it is valid, it sets it as the new contents of the line edit.

### bool QLineEdit::isReadOnly () const

Returns TRUE if the line edit is read only; otherwise returns FALSE. See the "readOnly" property for details.

### bool QLineEdit::isRedoAvailable () const

Returns TRUE if redo is available; otherwise returns FALSE. See the "redoAvailable" property for details.

### bool QLineEdit::isUndoAvailable () const

Returns TRUE if undo is available; otherwise returns FALSE. See the "undoAvailable" property for details.

### void QLineEdit::keyPressEvent ( QKeyEvent * e )`[virtual protected]`

Converts key press event e into a line edit action.

If Return or Enter is pressed and the current text is valid (or can be made valid by the validator), the signal returnPressed is emitted.

The default key bindings are listed in the detailed description.

Reimplemented from QWidget.

### QString QLineEdit::markedText () const

Returns the text selected by the user (e.g. by clicking and dragging), or QString::null if no text is selected. See the "markedText" property for details.

### int QLineEdit::maxLength () const

Returns the maximum permitted length of the text in the editor. See the "maxLength" property for details.

### QSize QLineEdit::minimumSizeHint () const`[virtual]`

Returns a minimum size for the line edit.

The width returned is enough for at least one character.

Reimplemented from QWidget.

### QChar QLineEdit::passwordChar () const

Returns the password character.

See also setPasswordChar().

### void QLineEdit::paste ()`[virtual slot]`

Inserts the clipboard's text at the cursor position, deleting any selected text.

If the end result is not acceptable for the current validator, nothing happens.

See also copy() and cut().

### void QLineEdit::redo ()`[virtual slot]`

Redoes the last operation

### void QLineEdit::repaintArea ( int from, int to )`[protected]`

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

Repaints all characters from from to to. If cursorPos is between from and to, ensures that cursorPos is visible.

### void QLineEdit::returnPressed ()`[signal]`

This signal is emitted when the Return or Enter key is pressed.

Example: popup/popup.cpp.

### void QLineEdit::selectAll ()`[virtual slot]`

Selects all the text (i.e. highlights it) and moves the cursor to the end. This is useful when a default value has been inserted because if the user types before clicking on the widget, the selected text will be erased.

See also setSelection() and deselect().

### QString QLineEdit::selectedText () const

Returns any text selected by the user or QString::null. See the "selectedText" property for details.

### void QLineEdit::selectionChanged ()`[signal]`

This signal is emitted whenever the selection changes.

See also hasSelectedText and selectedText.

### void QLineEdit::setAlignment ( int flag )`[virtual slot]`

Sets the alignment of the line edit to flag. See the "alignment" property for details.

### void QLineEdit::setCursorPosition ( int )`[virtual slot]`

Sets the current cursor position for this line edit. See the "cursorPosition" property for details.

### void QLineEdit::setDragEnabled ( bool b )`[virtual slot]`

Sets whether the lineedit starts a drag if the user presses and moves the mouse on some selected text to b. See the "dragEnabled" property for details.

### void QLineEdit::setEchoMode ( EchoMode )`[virtual slot]`

Sets the echo mode of the line edit. See the "echoMode" property for details.

### void QLineEdit::setEdited ( bool )

Sets the edited flag of the line edit. See the "edited" property for details.

### void QLineEdit::setFrame ( bool )`[virtual slot]`

Sets whether the line edit draws itself with a frame. See the "frame" property for details.

### void QLineEdit::setMaxLength ( int )`[virtual slot]`

Sets the maximum permitted length of the text in the editor. See the "maxLength" property for details.

### void QLineEdit::setPasswordChar ( QChar c )

Sets the password character to c.

See also passwordChar().

### void QLineEdit::setReadOnly ( bool )`[virtual slot]`

Sets whether the line edit is read only. See the "readOnly" property for details.

### void QLineEdit::setSelection ( int start, int length )`[virtual slot]`

Sets the selected area of this line edit to start at position start and be length characters long.

See also deselect(), selectAll() and getSelection().

### void QLineEdit::setText ( const QString & )`[virtual slot]`

Sets the text in the line. See the "text" property for details.

### void QLineEdit::setValidator ( const QValidator * v )`[virtual slot]`

Sets this line edit to accept input only as accepted by the validator, v, allowing arbitrary constraints on the text which may be entered.

If v == 0, setValidator() removes the current input validator. The initial setting is to have no input validator (i.e. any input is accepted up to maxLength()).

See also validator() and QValidator.

Examples: lineedits/lineedits.cpp and wizard/wizard.cpp.

### QSize QLineEdit::sizeHint () const`[virtual]`

Returns a recommended size for the widget.

The width returned, in pixels, is usually enough for about 15 to 20 characters.

Example: addressbook/centralwidget.cpp.

### QString QLineEdit::text () const

Returns the text in the line. See the "text" property for details.

### void QLineEdit::textChanged ( const QString & )`[signal]`

This signal is emitted whenever the text changes. The argument is the new text.

Examples: wizard/wizard.cpp and xform/xform.cpp.

### void QLineEdit::undo ()`[virtual slot]`

Undoes the last operation

### bool QLineEdit::validateAndSet ( const QString & newText, int newPos, int newMarkAnchor, int newMarkDrag )

Validates and perhaps sets this line edit to contain newText with the cursor at position newPos, with selected text from newMarkAnchor to newMarkDrag. Returns TRUE if it changes the line edit; otherwise returns FALSE.

Linebreaks in newText are converted to spaces, and the text is truncated to maxLength() before its validity is tested.

Repaints and emits textChanged() if appropriate.

### const QValidator * QLineEdit::validator () const

Returns a pointer to the current input validator, or 0 if no validator has been set.

See also setValidator().

Example: wizard/wizard.cpp.

## Property Documentation

### Alignment alignment

This property holds the alignment of the line edit.

Possible Values are Qt::AlignAuto, Qt::AlignLeft, Qt::AlignRight and Qt::AlignHCenter.

Attempting to set the alignment to an illegal flag combination does nothing.

See also Qt::AlignmentFlags.

Set this property's value with setAlignment() and get this property's value with alignment().

### int cursorPosition

This property holds the current cursor position for this line edit.

Setting the cursor position causes a repaint when appropriate.

Set this property's value with setCursorPosition() and get this property's value with cursorPosition().

### QString displayText

This property holds the text that is displayed.

If EchoMode is Normal this returns the same as text(); if EchoMode is Password it returns a string of asterisks the text().length() characters long, e.g. "******"; if EchoMode is NoEcho returns an empty string, "".

See also echoMode, text and EchoMode.

Get this property's value with displayText().

### bool dragEnabled

This property holds whether the lineedit starts a drag if the user presses and moves the mouse on some selected text.

Set this property's value with setDragEnabled() and get this property's value with dragEnabled().

### EchoMode echoMode

This property holds the echo mode of the line edit.

The initial setting is Normal, but QLineEdit also supports NoEcho and Password modes.

The widget's display and the ability to copy or drag the text is affected by this setting.

See also EchoMode and displayText.

Set this property's value with setEchoMode() and get this property's value with echoMode().

### bool edited

This property holds the edited flag of the line edit.

The edited flag is never read by QLineEdit; it has a default value of FALSE and is changed to TRUE whenever the user changes the line edit's contents.

This is useful for things that need to provide a default value but cannot find the default at once. Just start the line edit without the best default; when the default is known, check the edited() return value and set the line edit's contents if the user has not started editing the line edit.

Calling setText() resets the edited flag to FALSE.

Set this property's value with setEdited() and get this property's value with edited().

### bool frame

This property holds whether the line edit draws itself with a frame.

If enabled (the default) the line edit draws itself inside a two-pixel frame, otherwise the line edit draws itself without any frame.

Set this property's value with setFrame() and get this property's value with frame().

### bool hasMarkedText

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

This property holds whether part of the text has been selected by the user (e.g. by clicking and dragging).

Get this property's value with hasMarkedText().

See also selectedText.

### bool hasSelectedText

This property holds whether there is any text selected.

hasSelectedText() returns TRUE if some or all of the text has been selected by the user (e.g. by clicking and dragging); otherwise returns FALSE.

See also selectedText.

Get this property's value with hasSelectedText().

### QString markedText

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

This property holds the text selected by the user (e.g. by clicking and dragging), or QString::null if no text is selected.

Get this property's value with markedText().

See also hasSelectedText.

### int maxLength

This property holds the maximum permitted length of the text in the editor.

If the text is too long, it is truncated at the limit.

If truncation occurs any selected text will be unselected, the cursor position is set to 0 and the first part of the string is shown.

Set this property's value with setMaxLength() and get this property's value with maxLength().

### bool readOnly

This property holds whether the line edit is read only.

In read-only mode, the user can still copy the text to the clipboard or drag-and-drop the text, but cannot edit it.

QLineEdit does not show a cursor in read-only mode.

See also enabled.

Set this property's value with setReadOnly() and get this property's value with isReadOnly().

### bool redoAvailable

This property holds whether redo is available.

Get this property's value with isRedoAvailable().

### QString selectedText

This property holds any text selected by the user or QString::null.

Get this property's value with selectedText().

See also hasSelectedText.

### QString text

This property holds the text in the line.

Setting this property clears the selection, moves the cursor to the end of the line and resets the edited property to FALSE.

The text is truncated to maxLength() length.

Set this property's value with setText() and get this property's value with text().

### bool undoAvailable

This property holds whether undo is available.

Get this property's value with isUndoAvailable().

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