program crashes after assigning values to array elements

rezaMSLM

I have a class with name setaddress containing a structure that contains a 2D array:

int WaterMeterIDs[20][2];

namespace Ui {
class SetAddress;
}

class SetAddress : public QDialog
{
    Q_OBJECT

public:
    struct AddressList{
        int WaterMeterIDs[20][2];//the array
    };
    explicit SetAddress(QWidget *parent = 0);
    ~SetAddress();
    etc...
private:
    Ui::SetAddress *ui;
    AddressList m_address;

I want to save my data placed in qtablewidget cells to the array using these commands.
.cpp file:

void SetAddress::on_pushButton_apply_clicked()
{
    int rowscount = ui->tableWidget->rowCount();
//rowscount is always less than 20
    for(int j = 0; j < 2; j++){
        for(int i = 0; i < rowscount; i++){
            if(ui->tableWidget->item(i,j) != 0x0 ){//if cell is not empty
                 m_address.WaterMeterIDs[i][j] = ui->tableWidget->item(i,j)->text().toInt();//convert data to int and put it in array
                 qDebug()<<m_address.WaterMeterIDs[i][j];
            }
        }
    }
}

when I click on apply button the program works good(I can see array elements using qDebug()). but after I pressed the apply button if I press any other key even the close button(or even if I want to resize the window) program crashes!

jsulm

@rezaMSLM Please post the stack trace after crash.
Also, you do not check whether rowscount is bigger than 20!

rezaMSLM

@jsulm one note:
it doesn't crash in debug mode
only in release mode crashes!

jsulm

@rezaMSLM said in program crashes after assigning values to array elements:

it doesn't crash in debug mode
only in release mode crashes!

Strong sign for something wrong in your code.
You probably overwrite some memory.
Did you check that rowscount is <= 20?

Is there a reason why you have AddressList struct and why it is in public section?

rezaMSLM

@jsulm

if((ui->tableWidget->item(i,j) != 0x0) && (rowscount <= 20)){/*if cell is not empty && rowscount <= 20*/

I added rowscount check to the code
problem exists

@jsulm said in program crashes after assigning values to array elements:

Is there a reason why you have AddressList struct and why it is in public section?

no there is not special reason. is it unusual?

J.Hilk

@rezaMSLM said in program crashes after assigning values to array elements:

if((ui->tableWidget->item(i,j) != 0x0) && (rowscount <= 20)){/if cell is not empty && rowscount <= 20/

that is wrong, your array goes from 0 - 19, 20 is an invalid access

jsulm

@rezaMSLM said in program crashes after assigning values to array elements:

no there is not special reason. is it unusual?

I just don't see the point to have a struct containing an array and nothing else.
And everything not needed outside the class should be inside private section (information hiding).
Why not just declare

private:
int m_address[20][2];

?
Back to the crash: what is it? Is it SIGSEGV? Or something else?

rezaMSLM

@jsulm

@jsulm said in program crashes after assigning values to array elements:

I just don't see the point to have a struct containing an array and nothing else.

I'm planning to put and use some variables to the structure after solving this issue.

@jsulm said in program crashes after assigning values to array elements:

what is it? Is it SIGSEGV? Or something else?

how to know that?

jsulm

@rezaMSLM Start your app and when it crashes see what is printed in the console.

rezaMSLM

@jsulm

The program has unexpectedly finished.
The process was ended forcefully.
D:/Projects/Qt_ProjectFolder/build-Meter_Config-Desktop_Qt_5_9_6_MinGW_32bit-Release/release/Meter_Config.exe crashed.

jsulm

@rezaMSLM Did you see what @J-Hilk wrote?

rezaMSLM

@jsulm said in program crashes after assigning values to array elements:

@rezaMSLM Did you see what @J-Hilk wrote?

yes
if rowscount = 20 in for loop i have:

 for(int i = 0; i < count; i++){

meaning that maximum i = 19

although that is for safe side.
the number of rows in my tests is less than 10

jsulm

@rezaMSLM To be sure: if on_pushButton_apply_clicked() is not executed there is no crash?
If so what happens if you comment out

m_address.WaterMeterIDs[i][j] = ui->tableWidget->item(i,j)->text().toInt();

?
And do you use m_address.WaterMeterIDs somewhere else?

Maaz Momin

@rezaMSLM Do you have any pointer or member variable that doesn't have a default value. It doesn't crash in "Debug" mode because Debug mode initializes a few things and release mode doesn't. Hope this helps you in figuring out what is wrong :)

rezaMSLM

@jsulm said in program crashes after assigning values to array elements:

what happens if you comment out
m_address.WaterMeterIDs[i][j] = ui->tableWidget->item(i,j)->text().toInt();

if comment this, will not crash

@jsulm said in program crashes after assigning values to array elements:

And do you use m_address.WaterMeterIDs somewhere else?

no

jsulm

@rezaMSLM Well, then the only idea I have is that you're writing outside of the array boundaries.

Maaz Momin

@rezaMSLM can you add another qDebug before m_address.WaterMeterIDs[i][j] = ui->tableWidget->item(i,j)->text().toInt();

qDebug() << i << j;

rezaMSLM

@Maaz-Momin said in program crashes after assigning values to array elements:

Do you have any pointer or member variable that doesn't have a default value

only WaterMeterIDs[20][2] has not initial value

rezaMSLM

@Maaz-Momin said in program crashes after assigning values to array elements:

@rezaMSLM can you add another qDebug before m_address.WaterMeterIDs[i][j] = ui->tableWidget->item(i,j)->text().toInt();

qDebug() << i << j;

added it.
the log is correct
and then crashes with one click anywhere

J.Hilk

@rezaMSLM can you make a minimal compileable example, so that we could test it?