qtlist Query

[ebsaith]

I have x, y variables that are constantly changing
Only when user clicks a button will the x, y variable at that time be stored in array

Created button & linking to function ->no problem

not sure how to go about the array part
this is my code:
.h

private:    
    QList<int> ArrayX;
    QList<int> ArrayY;

private:    
    QList<int> ArrayX;
    QList<int> ArrayY;

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void my_qlabel::transferValues()
{
    //counter initialised to 0 in constructor
    Counter += 1;
    ArrayX[Counter] = x;
    ArrayY[Counter] = y;
}

void my_qlabel::transferValues()
{
    //counter initialised to 0 in constructor
    Counter += 1;
    ArrayX[Counter] = x;
    ArrayY[Counter] = y;
}

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Is the array Declared properly (array Has to be dynamic as it can increase as many time user pushes button)
Do I have to use the .append???

please provide me with sample code on qlist if possible?

Thanks

[anda_skoa]

Call the append() method or the push_back() method or use the << operator

ArrayX << x;
ArrayY << y;

ArrayX << x;
ArrayY << y;

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Might be even better to have only one list and have it store a structure that holds two values, e.g. a list of QPoint

Cheers,
_

[rawfool]

Yes you have to use append(). You don't need a counter.
Just do this -

ArrayX.append(x);
ArrayY.append(y);
 
//To access
ArrayX.at(index);
ArrayY.at(index);

ArrayX.append(x);
ArrayY.append(y);

//To access
ArrayX.at(index);
ArrayY.at(index);

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[ebsaith]

Thanks

Once array is completed its written to a file.txt

I need it to iterate through the list
& once completed all arrays must be cleared.

This is what I got so far:

...//[I]open file usual way[/I]
...//[I]create cout->stream[/I]
QTextStream stream(&file);
 
 stream <<  Counter << "\n";
 
 //prints to file -> x, y
 int i = 0;
 while(i <= Counter)
 {
    stream << ArrayX[i] << "\t" <<ArrayY[i] << "\n";
    i++;
 }

...//[I]open file usual way[/I]
...//[I]create cout->stream[/I]
QTextStream stream(&file);

 stream <<  Counter << "\n";
  
 //prints to file -> x, y
 int i = 0;
 while(i <= Counter)
 {
    stream << ArrayX[i] << "\t" <<ArrayY[i] << "\n";
    i++;
 }

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Is the output (stream) syntax correct
Need a counter for iterating while printing to file, Correct?
qDeleteAll() example, pls

output should be:
[Total points]
[list of points on seperate lines]

Thanks for the quick response

[rawfool]

int i = 0;
while( i < ArrayX.count() )   // ArrayX.size() also gives the total number of items
 {
    i++;
    //
 }

int i = 0;
while( i < ArrayX.count() )   // ArrayX.size() also gives the total number of items
 {
    i++;
    //
 }

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Make sure the ArrayX.count() & ArrayY.count() are equal if you are using values of both the arrays inside while.

[anda_skoa]

Make sure the ArrayX.count() & ArrayY.count() are equal if you are using values of both the arrays inside while.

Indeed. Hence my earlier suggestion to use a single array that contains both values in each entry

qDeleteAll() example, pls

What for? Your containers (lists) do not contain any pointers.

Cheers,
_

[rawfool]

Yes anda_skoa, you were spot on. He should probably use list of QPoint like you mentioned. But my answer was for the current situation

[ebsaith]

Im not sure if data is being stored in my array.
and when Itry to create a file displaying array --- program crashes

Heres my code: for sending array variables to filestream
my feeling the error is in this statement, not sure how to fix it?

int i = 0;
                            while( i <= ArrayX.count() )
                           {
                                    stream << ArrayY[i] << "\t" << ArrayX[i] << endl;
                                    i++;
                            }

int i = 0;
                            while( i <= ArrayX.count() )
                           {
                                    stream << ArrayY[i] << "\t" << ArrayX[i] << endl;
                                    i++;
                            }

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setting variables in array as above reply/post thread

please help

[nix]

Bound check : i < ArrayX.count()