qt保存数据系统崩溃

Question

qt上位机保存数据数据系统崩溃，提示

ASSERT failure in QList<T>::operator[]: "index out of range", file D:\Qt\Qt5.9.9\5.9.9\mingw53_32\include/QtCore/qlist.h, line 549

下面是保存数据的代码

```c++

void MainWindow::on_data_save_triggered()
{
    savedata_index = false;

    QStringList dataList;
    QString data;
    QString title;   //第一行标题
    QString filename=QFileDialog::getSaveFileName(this,tr("save file"),"",tr("表格(*.csv *.xls);;文本(*.txt);;所有(*.*)"));

    title.append("时间,滤波后,中位数");

    if(!filename.isNull())
    {
        qDebug()<<filename;
        QFile file(filename);

        if(file.open(QFile::WriteOnly | QFile::Text))//检测文件是否打开
        {
            QTextStream out(&file);       //分行写入文件
            out<<title + "\n";            //写第一行标题

            for(int m = 0; m < save_list.count(); m++)                 //写数据
            {
                for(int n = 0; n < 4; n++)
                {
                    data += (save_list[m * 4 + n] + ",");
                }
                out << data + "\n";
                data.clear();
            }

            file.close();
        }
    }
    else
    {
        qDebug()<<"cancle";
    }
}

```

Answer 1

报错提示一看就是越界了，再看for循环里面，假设save_list 长度10，m最大能到9，内层循环save_list[m * 4 + n] ，m=9时取值能到40，早就超过save_list 最大值，越界了；如果是save_list 每四个一组，外层循环要 m<save_list.count() / 4;