Remove spaces the from QString

Sucharek

Hi, I've been trying to remove the first space from a QString variable.
I'm making a all 10 fingers program (for keyboard) and I'm deleting characters one by one, but I'm having problem with spaces.
Here's my mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"

const QString article = "A quick red fox jumped over a lazy dog";

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    ui->textEdit_Article->setText(article);
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_lineEdit_TextInput_textChanged(const QString &arg1)
{
    QString word = arg1;
    QString lastCharacter = arg1.back();
    QString firstCharacter = arg1.front();
    QString articleThing = article.front();
    QString articleQ;
    if (lastCharacter == " ")
    {
        ui->lineEdit_TextInput->setText("");
        word = "";
    }
    if (firstCharacter == articleThing)
    {
        std::string articleRemove = article.toUtf8().constData();
        if (firstCharacter == " ")
        {
            articleQ = articleQ.trimmed();
        } else if (firstCharacter == "u\0000") {
            articleQ = articleQ.trimmed();
        } else {
            articleRemove = articleRemove.erase(0,1);
        }
        articleQ = QString::fromStdString(articleRemove);
        ui->textEdit_Article->setText(articleQ);
    }
}

Here's a snippet from mainwindow.cpp of the text characters deleting when it's typed:

void MainWindow::on_lineEdit_TextInput_textChanged(const QString &arg1)
{
    QString word = arg1;
    QString lastCharacter = arg1.back();
    QString firstCharacter = arg1.front();
    QString articleThing = article.front();
    QString articleQ;
    if (lastCharacter == " ")
    {
        ui->lineEdit_TextInput->setText("");
        word = "";
    }
    if (firstCharacter == articleThing)
    {
        std::string articleRemove = article.toUtf8().constData();
        if (firstCharacter == " ")
        {
            articleQ = articleQ.trimmed();
        } else if (firstCharacter == "u\0000") {
            articleQ = articleQ.trimmed();
        } else {
            articleRemove = articleRemove.erase(0,1);
        }
        articleQ = QString::fromStdString(articleRemove);
        ui->textEdit_Article->setText(articleQ);
    }
}

ghutchis

You can always try QString::trimmed():
https://doc.qt.io/qt-5/qstring.html#trimmed

Sucharek

Hi @ghutchis, I've used QString::trimmed() right here:

if (firstCharacter == articleThing)
    {
        std::string articleRemove = article.toUtf8().constData();
        if (firstCharacter == " ")
        {
            articleQ = articleQ.trimmed();
        } else if (firstCharacter == "u\0000") {
            articleQ = articleQ.trimmed();
        } else {
            articleRemove = articleRemove.erase(0,1);
        }
        articleQ = QString::fromStdString(articleRemove);
        ui->textEdit_Article->setText(articleQ);
    }

Another of the problem I have, are that when I press space and qDebug it, it prints twice with:
" "
and
"u\0000"
EDIT: It prints the first character as the outputs shown up. I'm printing this:
QString firstCharacter = arg1.front();

JoeCFD

str = str.simplified();

Ketan__Patel__0011

@Sucharek

mystring = mystring.replace(" ","");

Sucharek

Hi, so @JoeCFD solution worked perfectly.
@Ketan__Patel__0011's solution did remove the spaces, but it removed EVERY space.
I had some things wrong in my code too, but anyway, thanks for the solutions :D

JonB

@Sucharek said in Remove spaces the from QString:

I've been trying to remove the first space from a QString variable.

The quickest (short and reasonably performant) code to do just this is something like:

if (word.startsWith(' '))
    word.remove(0, 1);

QString::simplified() does quite a bit more than "remove the first space". Up to you. If you have given up on moving a QString over to a std::string, and then back again, to do your work, that is good.