How to Retrieve the Data from a Plain Text Edit Element in a Qt Widget Application in C++

In this article, we show how to retrieve the data from a plain text edit element in a Qt widget application in C++.

A plainTextEdit is an element that is the equivalent of a textarea input element in HTML.

This is shown below.

So a plainTextEdit is an element in which a program can obtain any type of plain text from a user. By plain text, we mean text that isn't encoded in a language such as HTML. It's just plain text without any code elements, such as "I live in New York".

So how do we place a plainTextEdit element in a program and retrieve the text from it which a user enters?

This is what we go over in this program.

So to place a plainTextEdit element in a program, we place the following in the "widgets.ui" file.

<widget class="QPlainTextEdit" name="plainTextEdit"> <property name="geometry"> <rect> <x>90</x> <y>330</y> <width>104</width> <height>71</height> </rect> </property> <property name="plainText"> <string/> </property> </widget>

So in order to understand this plainTextEdit widget, you can see that the widget is of class "QPlainTextEdit". Every plainTextEdit element is of this class in a Qt widget application. The name, however, can change to identify the specific plainTextEdit you are referring to. By default, the first plainTextEdit element in an application will be "plainTextEdit". Each additional plainTextEdit element will be enumerated. For example, the second plainTextEdit element in an application will have the name, "plainTextEdit_2". The third will have the name, "plainTextEdit_3", etc. Of course, these name values can be changed manually. Each has a unique name to be able to reference each specific plainTextEdit element if you have more than 1 in an application.

So now that we have this plainTextEdit element in our "widget.ui" application, we need to go to our next page.

Next we go to the "widget.h" header file.

Since we have to create a variable that stores the value from the plainTextEdit element, we need to declare a variable that will be used to store this value. The declaration of variables go into the "widget.h" header file under the private keyword.

So the full contents of the "widget.h" file is shown below.

#ifndef WIDGET_H #define WIDGET_H #include <QWidget> #include <QString> QT_BEGIN_NAMESPACE namespace Ui { class Widget; } QT_END_NAMESPACE class Widget : public QWidget { Q_OBJECT public: Widget(QWidget *parent = nullptr); ~Widget(); private slots: void on_pushButton_clicked(); private: Ui::Widget *ui; QString plaintextvalue; }; #endif // WIDGET_H

So you see that under the private keyword, we have an integer named plaintextvalue. This will be used in our application to store the data the user types into the .

So now and the last file we go to is the "widget.cpp" file.

In this file, we retrieve the data from the plainTextEdit element that the user enters and we output this value in the application output using the qDebug() function.

The contents of this file is shown below.

#include "widget.h" #include "ui_widget.h" #include <QDebug> Widget::Widget(QWidget *parent) : QWidget(parent) , ui(new Ui::Widget) { ui->setupUi(this); } Widget::~Widget() { delete ui; } void Widget::on_pushButton_clicked() { plaintextvalue= ui->plainTextEdit->toPlainText(); qDebug() << "Text: " << plaintextvalue; }

In this application, we retrieve the data from the plainTextEdit element and store it into the plaintextvalue variable we created in the "widget.h" file.

This application assumes that you have a push button in your application, because it retrieves the value from the plainTextEdit element upon the pressing the pushbutton.

So in our Qt widget application, we have the plainTextEdit element and a pushbutton whose name is "pushButton".

The retrieval of the value of the plainTextEdit element is done when the push button is clicked.

So inside of this clicked function, we specify the variable, plaintextvalue, and set it equal to, ui->plainTextEdit->toPlainText();

ui references the user interface.

plainTextEdit is the name attribute of the plainTextEdit element we are targeting.

toPlainText() is the value specified in the plainTextEdit element.

Now to show you what value we get, we use the qDebug() function to output the data from the plainTextEdit element.

Let's say, you were to create another plainTextEdit element. Say you need to create a program that retrieves multiple sets of data from a user.

So in order to now deal with 2 plainTextEdit elements, you need to add another plainTextEdit element.

If you use the Design element of the Qt software to add another plainTextEdit element, this will be the code you will add.

<widget class="QPlainTextEdit" name="plainTextEdit_2"> <property name="geometry"> <rect> <x>90</x> <y>330</y> <width>104</width> <height>71</height> </rect> </property> <property name="plainText"> <string/> </property> </widget>

After this, you need to declare another variable in the "widget.h" file in order to store the value of the second plainTextEdit element. So add, int plaintextvalue2, to the "widget.h" file under the private keyword.

Then after that, you need to modify the "widget.ui" file to save the value from the second plainTextEdit element to the variable, plaintextvalue2.

This is shown below.

#include "widget.h" #include "ui_widget.h" #include <QDebug> Widget::Widget(QWidget *parent) : QWidget(parent) , ui(new Ui::Widget) { ui->setupUi(this); } Widget::~Widget() { delete ui; } void Widget::on_pushButton_clicked() { plaintextvalue= ui->plainTextEdit->value(); plaintextvalue2= ui->plainTextEdit_2->value(); qDebug() << "Text: " << plaintextvalue; qDebug() << "Text 2: " << plaintextvalue2; }

So now we've retrieved both values from the 2 plainTextEdit elements.

Since the name attribute of the second element is "plainTextEdit_2", we use this to retrieve the value from the second plainTextEdit element.

Again, that is the name that the software automatically generates if you don't change it. You can change that name. You just have to make sure that when referencing the element, you refer to it with the changed name.

And this is how to retrieve the data from a plain text edit element in a Qt widget in C++.

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