- Qt 6.10
- Qt Widgets
- C++ Classes
- QLineEdit
- Qt 6.10.2 Reference Documentation

# QLineEdit Class

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

Header: | `#include <QLineEdit>`
CMake: | `find_package(Qt6 REQUIRED COMPONENTS Widgets)` `target_link_libraries(mytarget PRIVATE Qt6::Widgets)`
qmake: | `QT += widgets`
Inherits: | QWidget

- List of all members, including inherited members

## Public Types

enum | ActionPosition { LeadingPosition, TrailingPosition }
enum | EchoMode { Normal, NoEcho, Password, PasswordEchoOnEdit }

## Properties

- acceptableInput : const bool
- alignment : Qt::Alignment
- clearButtonEnabled : bool
- cursorMoveStyle : Qt::CursorMoveStyle
- cursorPosition : int
- displayText : const QString
- dragEnabled : bool
- echoMode : EchoMode
- frame : bool
- hasSelectedText : const bool

- inputMask : QString
- maxLength : int
- modified : bool
- placeholderText : QString
- readOnly : bool
- redoAvailable : const bool
- selectedText : const QString
- text : QString
- undoAvailable : const bool

## Public Functions

| QLineEdit(QWidget *parent = nullptr)
| QLineEdit(const QString &contents, QWidget *parent = nullptr)
virtual | ~QLineEdit()
Qt::Alignment | alignment() const
void | backspace()
QMenu * | createStandardContextMenu()
void | cursorBackward(bool mark, int steps = 1)
void | cursorForward(bool mark, int steps = 1)
Qt::CursorMoveStyle | cursorMoveStyle() const
int | cursorPosition() const
int | cursorPositionAt(const QPoint &pos)
void | cursorWordBackward(bool mark)
void | cursorWordForward(bool mark)
void | del()
void | deselect()
QString | displayText() const
bool | dragEnabled() const
QLineEdit::EchoMode | echoMode() const
void | end(bool mark)
bool | hasAcceptableInput() const
bool | hasFrame() const
bool | hasSelectedText() const
void | home(bool mark)
QString | inputMask() const
void | insert(const QString &newText)
bool | isClearButtonEnabled() const
bool | isModified() const
bool | isReadOnly() const
bool | isRedoAvailable() const
bool | isUndoAvailable() const
int | maxLength() const
QString | placeholderText() const
QString | selectedText() const
int | selectionEnd() const
int | selectionLength() const
int | selectionStart() const
void | setAlignment(Qt::Alignment flag)
void | setClearButtonEnabled(bool enable)
void | setCursorMoveStyle(Qt::CursorMoveStyle style)
void | setCursorPosition(int)
void | setDragEnabled(bool b)
void | setEchoMode(QLineEdit::EchoMode)
void | setFrame(bool)
void | setInputMask(const QString &inputMask)
void | setMaxLength(int)
void | setModified(bool)
void | setPlaceholderText(const QString &)
void | setReadOnly(bool)
void | setSelection(int start, int length)
void | setTextMargins(const QMargins &margins)
void | setTextMargins(int left, int top, int right, int bottom)
void | setValidator(const QValidator *v)
QString | text() const
QMargins | textMargins() const
const QValidator * | validator() const

## Reimplemented Public Functions

virtual bool | event(QEvent *e) override
virtual QVariant | inputMethodQuery(Qt::InputMethodQuery property) const override
virtual QSize | minimumSizeHint() const override
virtual QSize | sizeHint() const override
virtual void | timerEvent(QTimerEvent *e) override

## Public Slots

void | clear()
void | copy() const
void | cut()
void | paste()
void | redo()
void | selectAll()
void | setText(const QString &)
void | undo()

## Signals

void | textChanged(const QString &)

## Protected Functions

QRect | cursorRect() const
virtual void | initStyleOption(QStyleOptionFrame *option) const

## Reimplemented Protected Functions

virtual void | changeEvent(QEvent *ev) override
virtual void | contextMenuEvent(QContextMenuEvent *event) override
virtual void | focusInEvent(QFocusEvent *e) override
virtual void | focusOutEvent(QFocusEvent *e) override
virtual void | inputMethodEvent(QInputMethodEvent *e) override
virtual void | keyPressEvent(QKeyEvent *event) override
virtual void | keyReleaseEvent(QKeyEvent *e) override
virtual void | mouseDoubleClickEvent(QMouseEvent *e) override
virtual void | mouseMoveEvent(QMouseEvent *e) override
virtual void | mousePressEvent(QMouseEvent *e) override
virtual void | mouseReleaseEvent(QMouseEvent *e) override
virtual void | paintEvent(QPaintEvent *) override

## Detailed Description

A line edit allows users to enter and edit a single line of plain text with useful 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.

QTextEdit is a related class that allows multi-line, rich text editing.

### Constraining Text

Use maxLength to define the maximum permitted length of a text. You can use a inputMask and setValidator() to further constrain the text content.

### Editing Text

You can change the text with setText() or insert(). Use text() to retrieve the text and displayText() to retrieve the displayed text (which may be different, see EchoMode). You can select the text with setSelection() or selectAll(), and you can cut(), copy(), and paste() the selection. To align the text, use setAlignment().

When the text changes, the textChanged() signal is emitted. When the text changes in some other way than by calling setText(), the textEdited() signal is emitted. When the cursor is moved, the cursorPositionChanged() signal is emitted. And when the Return or Enter key is selected, the returnPressed() signal is emitted.

When text editing is finished, either because the line edit lost focus or Return/Enter was selected, the editingFinished() signal is emitted.

If the line edit focus is lost without any text changes, the editingFinished() signal won't be emitted.

If there is a validator set on the line edit, the returnPressed()/editingFinished() signals will only be emitted if the validator returns QValidator::Acceptable.

For more information on the many ways that QLineEdit can be used, see Line Edits Example, which also provides a selection of line edit examples that show the effects of various properties and validators on the input and output supplied by the user.

### Setting a Frame

By default, QLineEdits have a frame as specified in the platform style guides. You can turn the frame off by calling setFrame(false).

### Default Key Bindings

The table below describes the default key bindings.

Note: The line edit also provides a context menu (usually invoked by a right-click) that presents some of the editing options listed below.

Keystroke | Action
--- | ---
Left Arrow | Moves the cursor one character to the left.
Shift+Left Arrow | Moves and selects text one character to the left.
Right Arrow | Moves the cursor one character to the right.
Shift+Right Arrow | Moves and selects text one character to the right.
Home | Moves the cursor to the beginning of the line.
End | Moves the cursor to the end of the line.
Backspace | Deletes the character to the left of the cursor.
Ctrl+Backspace | Deletes the word to the left of the cursor.
Delete | Deletes the character to the right of the cursor.
Ctrl+Delete | Deletes the word to the right of the cursor.
Ctrl+A | Selects all.
Ctrl+C | Copies the selected text to the clipboard.
Ctrl+Insert | Copies the selected text to the clipboard.
Ctrl+K | Deletes to the end of the line.
Ctrl+V | Pastes the clipboard text into line edit.
Shift+Insert | Pastes the clipboard text into line edit.
Ctrl+X | Deletes the selected text and copies it to the clipboard.
Shift+Delete | Deletes the selected text and copies it to the clipboard.
Ctrl+Z | Undoes the last operation.
Ctrl+Y | Redoes the last undone operation.

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

See also QTextEdit, QLabel, QComboBox, and Line Edits Example.

## Member Type Documentation

### enum QLineEdit::ActionPosition

This enum type describes how a line edit should display the action widgets to be added.

Constant | Value | Description
--- | --- | ---
`QLineEdit::LeadingPosition` | `0` | The widget is displayed to the left of the text when using layout direction `Qt::LeftToRight` or to the right when using `Qt::RightToLeft`, respectively.
`QLineEdit::TrailingPosition` | `1` | The widget is displayed to the right of the text when using layout direction `Qt::LeftToRight` or to the left when using `Qt::RightToLeft`, respectively.

See also addAction(), removeAction(), and QWidget::layoutDirection.

### enum QLineEdit::EchoMode

This enum type describes how a line edit should display its contents.

Constant | Value | Description
--- | --- | ---
`QLineEdit::Normal` | `0` | Display characters as they are entered. This is the default.
`QLineEdit::NoEcho` | `1` | Do not display anything. This may be appropriate for passwords where even the length of the password should be kept secret.
`QLineEdit::Password` | `2` | Display platform-dependent password mask characters instead of the characters actually entered.
`QLineEdit::PasswordEchoOnEdit` | `3` | Display characters only while they are entered. Otherwise, display characters as with `Password`.

See also setEchoMode() and echoMode().

## Property Documentation

### `[read-only]` acceptableInput : const bool

This property holds whether the input satisfies the inputMask and the validator.

By default, this property is `true`.

Access functions:

bool | hasAcceptableInput() const

See also setInputMask() and setValidator().

### alignment : Qt::Alignment

This property holds the alignment of the line edit.

Both horizontal and vertical alignment is allowed here, Qt::AlignJustify will map to Qt::AlignLeft.

By default, this property contains a combination of Qt::AlignLeft and Qt::AlignVCenter.

Access functions:

Qt::Alignment | alignment() const
void | setAlignment(Qt::Alignment flag)

See also Qt::Alignment.

### clearButtonEnabled : bool

This property holds whether the line edit displays a clear button when it is not empty.

If enabled, the line edit displays a trailing clear button when it contains some text. Otherwise, the line edit does not show a clear button (the default).

Access functions:

bool | isClearButtonEnabled() const
void | setClearButtonEnabled(bool enable)

See also addAction() and removeAction().

### cursorMoveStyle : Qt::CursorMoveStyle

This property holds the movement style of the cursor in this line edit.

When this property is set to Qt::VisualMoveStyle, the line edit will use a visual movement style. Using the left arrow key will always cause the cursor to move left, regardless of the text's writing direction. The same behavior applies to the right arrow key.

When the property is set to Qt::LogicalMoveStyle (the default), within a left-to-right (LTR) text block, using the left arrow key will increase the cursor position, whereas using the right arrow key will decrease the cursor position. If the text block is right-to-left (RTL), the opposite behavior applies.

Access functions:

Qt::CursorMoveStyle | cursorMoveStyle() const
void | setCursorMoveStyle(Qt::CursorMoveStyle style)

### cursorPosition : int

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

Setting the cursor position causes a repaint when appropriate.

By default, this property contains a value of 0.

Access functions:

int | cursorPosition() const
void | setCursorPosition(int)

### `[read-only]` displayText : const QString

This property holds the displayed text.

If echoMode is Normal, this returns the same as text(). If EchoMode is Password or PasswordEchoOnEdit, it returns a string of platform-dependent password mask characters (e.g. "******"). If EchoMode is NoEcho, it returns an empty string.

By default, this property contains an empty string.

Access functions:

QString | displayText() const

See also setEchoMode(), text(), and EchoMode.

### dragEnabled : bool

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

Dragging is disabled by default.

Access functions:

bool | dragEnabled() const
void | setDragEnabled(bool b)

### echoMode : EchoMode

This property holds the line edit's echo mode.

The echo mode determines how the text entered in the line edit is displayed (or echoed) to the user.

The most common setting is Normal, in which the text entered by the user is displayed verbatim. QLineEdit also supports modes that allow the entered text to be suppressed or obscured: these include NoEcho, Password and PasswordEchoOnEdit.

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

By default, this property is set to Normal.

Access functions:

QLineEdit::EchoMode | echoMode() const
void | setEchoMode(QLineEdit::EchoMode)

See also EchoMode and displayText().

### frame : bool

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

If enabled (the default), the line edit draws itself inside a frame. Otherwise, the line edit draws itself without any frame.

Access functions:

bool | hasFrame() const
void | setFrame(bool)

### `[read-only]` hasSelectedText : const bool

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. Otherwise, it returns `false`.

By default, this property is `false`.

Access functions:

bool | hasSelectedText() const

See also selectedText().

### inputMask : QString

This property holds the validation input mask.

Sets the QLineEdit's validation mask. Validators can be used instead of, or in conjunction with masks; see setValidator(). The default is an empty string, which means that no input mask is used.

To unset the mask and return to normal QLineEdit operation, pass an empty string.

The input mask is an input template string. It can contain the following elements:

Mask Characters | Defines the Category of input characters that are considered valid in this position.
Meta Characters | Various special meanings (see details below).
Separators | All other characters are regarded as immutable separators.

The following table shows the mask and meta characters that can be used in an input mask.

Mask Character | Meaning
--- | ---
`A` | Character of the Letter category required, such as A-Z, a-z.
`a` | Character of the Letter category permitted but not required.
`N` | Character of the Letter or Number category required, such as A-Z, a-z, 0-9.
`n` | Character of the Letter or Number category permitted but not required.
`X` | Any non-blank character required.
`x` | Any non-blank character permitted but not required.
`9` | Character of the Number category required, such as 0-9.
`0` | Character of the Number category permitted but not required.
`D` | Character of the Number category and larger than zero required, such as 1-9.
`d` | Character of the Number category and larger than zero permitted but not required, such as 1-9.
`#` | Character of the Number category, or plus/minus sign permitted but not required.
`H` | Hexadecimal character required. A-F, a-f, 0-9.
`h` | Hexadecimal character permitted but not required.
`B` | Binary character required. 0-1.
`b` | Binary character permitted but not required.
Meta Character | Meaning
`>` | All following alphabetic characters are uppercased.
`<` | All following alphabetic characters are lowercased.
`!` | Switch off case conversion.
`;c` | Terminates the input mask and sets the blank character to c.
`[ ] { }` | Reserved.
`\` | Use `\` to escape the special characters listed above to use them as separators.

When created or cleared, the line edit will be filled with a copy of the input mask string where the meta characters have been removed, and the mask characters have been replaced with the blank character (by default, a `space`).

When an input mask is set, the text() method returns a modified copy of the line edit content where all the blank characters have been removed. The unmodified content can be read using displayText().

The hasAcceptableInput() method returns false if the current content of the line edit does not fulfill the requirements of the input mask.

Examples:

Mask | Notes
--- | ---
`000.000.000.000;_` | IP address; blanks are `_`.
`HH:HH:HH:HH:HH:HH;_` | MAC address
`0000-00-00` | ISO Date; blanks are `space`
`>AAAAA-AAAAA-AAAAA-AAAAA-AAAAA;#` | License number; blanks are `#` and all (alphabetic) characters are converted to uppercase.

To get range control (e.g., for an IP address) use masks together with validators.

Access functions:

QString | inputMask() const
void | setInputMask(const QString &inputMask)

See also maxLength, QChar::isLetter(), QChar::isNumber(), and QChar::digitValue().

### maxLength : int

This property holds the maximum permitted length of the text.

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.

If the line edit has an input mask, the mask defines the maximum string length.

By default, this property contains a value of 32767.

Access functions:

int | maxLength() const
void | setMaxLength(int)

See also inputMask.

### modified : bool

This property holds whether the line edit's contents has been modified by the user.

The modified 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 do not start out knowing what the default should be (for example, it depends on other fields on the form). Start the line edit without the best default, and when the default is known, if modified() returns `false` (the user hasn't entered any text), insert the default value.

Calling setText() resets the modified flag to false.

Access functions:

bool | isModified() const
void | setModified(bool)

### placeholderText : QString

This property holds the line edit's placeholder text.

Setting this property makes the line edit display a grayed-out placeholder text as long as the line edit is empty.

Normally, an empty line edit shows the placeholder text even when it has focus. However, if the content is horizontally centered, the placeholder text is not displayed under the cursor when the line edit has focus.

By default, this property contains an empty string.

Access functions:

QString | placeholderText() const
void | setPlaceholderText(const QString &)

See also text().

### readOnly : bool

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 (if echoMode() is Normal), but cannot edit it.

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

By default, this property is `false`.

Access functions:

bool | isReadOnly() const
void | setReadOnly(bool)

See also setEnabled().

### `[read-only]` redoAvailable : const bool

This property holds whether redo is available.

Redo becomes available once the user has performed one or more undo operations on the text in the line edit.

By default, this property is `false`.

Access functions:

bool | isRedoAvailable() const

### `[read-only]` selectedText : const QString

This property holds the selected text.

If there is no selected text, this property's value is an empty string.

By default, this property contains an empty string.

Access functions:

QString | selectedText() const

See also hasSelectedText().

### text : QString

This property holds the line edit's text.

Setting this property clears the selection, clears the undo/redo history, moves the cursor to the end of the line, and resets the modified property to false. The text is not validated when inserted with setText().

The text is truncated to maxLength() length.

By default, this property contains an empty string.

Access functions:

QString | text() const
void | setText(const QString &)

Notifier signal:

void | textChanged(const QString &)

See also insert() and clear().

### `[read-only]` undoAvailable : const bool

This property holds whether undo is available.

Undo becomes available once the user has modified the text in the line edit.

By default, this property is `false`.

Access functions:

bool | isUndoAvailable() const

## Member Function Documentation

### `[explicit]` QLineEdit::QLineEdit(QWidget *parent = nullptr)

Constructs a line edit with no text.

The maximum text length is set to 32767 characters.

The parent argument is sent to the QWidget constructor.

See also setText() and setMaxLength().

### `[explicit]` QLineEdit::QLineEdit(const QString &contents, QWidget *parent = nullptr)

Constructs a line edit containing the text contents as a child of parent.

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

See also text() and setMaxLength().

### `[virtual noexcept]` QLineEdit::~QLineEdit()

Destroys the line edit.

### void QLineEdit::backspace()

If no text is selected, deletes the character to the left of the text cursor, and moves the cursor one position to the left. If any text is selected, the cursor is moved to the beginning of the selected text, and the selected text is deleted.

See also del().

### `[override virtual protected]` void QLineEdit::changeEvent(QEvent *ev)

Reimplements: QWidget::changeEvent(QEvent *event).

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

Clears the contents of the line edit.

See also setText() and insert().

### `[override virtual protected]` void QLineEdit::contextMenuEvent(QContextMenuEvent *event)

Reimplements: QWidget::contextMenuEvent(QContextMenuEvent *event).

Shows the standard context menu created with createStandardContextMenu().

If you do not want the line edit to have a context menu, you can set its contextMenuPolicy to Qt::NoContextMenu. To customize the context menu, reimplement this function. To extend the standard context menu, reimplement this function, call createStandardContextMenu(), and extend the menu returned.

     void LineEdit::contextMenuEvent(QContextMenuEvent *event)
     {
         QMenu *menu = createStandardContextMenu();
         menu->addAction(tr("My Menu Item"));
         //...
         menu->exec(event->globalPos());
         delete menu;
     }

The event parameter is used to obtain the position where the mouse cursor was when the event was generated.

See also setContextMenuPolicy().

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

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

See also cut() and paste().

### QMenu *QLineEdit::createStandardContextMenu()

Creates the standard context menu, which is shown when the user clicks on the line edit with the right mouse button. It is called from the default contextMenuEvent() handler. 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().

### int QLineEdit::cursorPositionAt(const QPoint &pos)

Returns the cursor position under the point pos.

### `[protected]` QRect QLineEdit::cursorRect() const

Returns a rectangle that includes the line edit cursor.

### 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().

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

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 without deleting.

See also copy(), paste(), and setValidator().

### void QLineEdit::del()

If no text is selected, deletes the character to the right of the text cursor. If any text is selected, the cursor is moved to the beginning of the selected text, and the selected text is deleted.

See also backspace().

### void QLineEdit::deselect()

Deselects any selected text.

See also setSelection() and selectAll().

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

Moves the text cursor to the end of the line unless it is already there. 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().

### `[override virtual]` bool QLineEdit::event(QEvent *e)

Reimplements: QWidget::event(QEvent *event).

### `[override virtual protected]` void QLineEdit::focusInEvent(QFocusEvent *e)

Reimplements: QWidget::focusInEvent(QFocusEvent *event).

### `[override virtual protected]` void QLineEdit::focusOutEvent(QFocusEvent *e)

Reimplements: QWidget::focusOutEvent(QFocusEvent *event).

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

Moves the text cursor to the beginning of the line unless it is already there. 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().

### `[virtual protected]` void QLineEdit::initStyleOption(QStyleOptionFrame *option) const

Initialize option with the values from this QLineEdit. This method is useful for subclasses when they need a QStyleOptionFrame, but don't want to fill in all the information themselves.

See also QStyleOption::initFrom().

### `[override virtual protected]` void QLineEdit::inputMethodEvent(QInputMethodEvent *e)

Reimplements: QWidget::inputMethodEvent(QInputMethodEvent *event).

### `[override virtual]` QVariant QLineEdit::inputMethodQuery(Qt::InputMethodQuery property) const

Reimplements: QWidget::inputMethodQuery(Qt::InputMethodQuery query) const.

### void QLineEdit::insert(const QString &newText)

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

See also setText() and clear().

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

Reimplements: QWidget::keyPressEvent(QKeyEvent *event).

Converts the given key press event into a line edit action.

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

See also Default Key Bindings.

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

Reimplements: QWidget::keyReleaseEvent(QKeyEvent *event).

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

Reimplements an access function for property: QWidget::minimumSizeHint.

Returns a minimum size for the line edit.

The width returned is usually enough for at least one character.

### `[override virtual protected]` void QLineEdit::mouseDoubleClickEvent(QMouseEvent *e)

Reimplements: QWidget::mouseDoubleClickEvent(QMouseEvent *event).

### `[override virtual protected]` void QLineEdit::mouseMoveEvent(QMouseEvent *e)

Reimplements: QWidget::mouseMoveEvent(QMouseEvent *event).

### `[override virtual protected]` void QLineEdit::mousePressEvent(QMouseEvent *e)

Reimplements: QWidget::mousePressEvent(QMouseEvent *event).

### `[override virtual protected]` void QLineEdit::mouseReleaseEvent(QMouseEvent *e)

Reimplements: QWidget::mouseReleaseEvent(QMouseEvent *event).

### `[override virtual protected]` void QLineEdit::paintEvent(QPaintEvent *)

Reimplements: QWidget::paintEvent(QPaintEvent *event).

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

Inserts the clipboard's text at the cursor position, deleting any selected text, providing the line edit is not read-only.

If the end result would be invalid to the current validator, nothing happens.

See also copy() and cut().

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

Redoes the last operation if redo is available.

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

Selects all the text (highlights it) and moves the cursor to the end.

Note: 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 deleted.

See also setSelection() and deselect().

### int QLineEdit::selectionEnd() const

Returns the index of the character directly after the selection in the line edit (or -1 if no text is selected).

See also selectedText(), selectionStart(), and selectionLength().

### int QLineEdit::selectionLength() const

Returns the length of the selection.

See also selectedText(), selectionStart(), and selectionEnd().

### int QLineEdit::selectionStart() const

Returns the index of the first selected character in the line edit (or -1 if no text is selected).

See also selectedText(), selectionEnd(), and selectionLength().

### void QLineEdit::setSelection(int start, int length)

Selects text from position start and for length characters. Negative lengths are allowed.

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

### void QLineEdit::setTextMargins(const QMargins &margins)

Sets the margins around the text inside the frame.

See also textMargins().

### void QLineEdit::setTextMargins(int left, int top, int right, int bottom)

Sets the margins around the text inside the frame to have the sizes left, top, right, and bottom.

See also textMargins().

### void QLineEdit::setValidator(const QValidator *v)

Sets the validator for values of line edit to v.

The line edit's returnPressed() and editingFinished() signals will only be emitted if v validates the line edit's content as Acceptable. The user may change the content to any Intermediate value during editing, but will be prevented from editing the text to a value that v validates as Invalid.

This allows you to constrain the text that will be stored when editing is done while leaving users with enough freedom to edit the text from one valid state to another.

To remove the current input validator, pass `nullptr`. The initial setting is to have no input validator (any input is accepted up to maxLength()).

See also validator(), hasAcceptableInput(), QIntValidator, QDoubleValidator, and QRegularExpressionValidator.

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

Reimplements an access function for property: QWidget::sizeHint.

Returns a recommended size for the widget.

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

### QMargins QLineEdit::textMargins() const

Returns the widget's text margins.

See also setTextMargins().

### `[override virtual]` void QLineEdit::timerEvent(QTimerEvent *e)

Reimplements: QObject::timerEvent(QTimerEvent *event).

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

Undoes the last operation if undo is available. Deselects any current selection, and updates the selection start to the current cursor position.

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

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

See also setValidator().