QMap in QList | i can get value but i can`t set value

[petrusPL]

Hi
i dynamicly create a QMap and put it on QList

QMap<QPoint, int> myMap;
 
 for(int i=0; i<5; i++)
    {
        for(int j=0; j<5; j++)
        {
            myMap.insert(QPoint(j, i), 0);
        }
    }
 
this->MapList.insert(0, myMap);

QMap<QPoint, int> myMap;

 for(int i=0; i<5; i++)
    {
        for(int j=0; j<5; j++)
        {
            myMap.insert(QPoint(j, i), 0);
        }
    }

this->MapList.insert(0, myMap);

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and i can get the value but i can`t set it :C

1) this->MapList.at(0)[QPoint(x,y)]  = 1;
 
2) this->MapList.at(0).insert(QPoint(x,y), 1);

1) this->MapList.at(0)[QPoint(x,y)]  = 1;

2) this->MapList.at(0).insert(QPoint(x,y), 1);

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1) lvalue required as left operand of assignment

2)passing 'const QMap<QPoint, int>' as 'this' argument of 'QMap<Key, T>::iterator QMap<Key, T>::insert(const Key&, const T&) [with Key = QPoint; T = int]' discards qualifiers [-fpermissive]

why it dont work ?

[jesse_mark]

1) this->MapList.at(0)[QPoint(x,y)] = 1;

what this line suppose to do ??

2) this->MapList.at(0).insert(QPoint(x,y), 1);

you cannot insert because you are using ( at (index)), this method is used to retrieve value only, not to insert or edit.

[petrusPL]

1)line suppose to insert value 1 to QPoint(x,y) key in QMap

((((
i was thinking that this->MapList.at(0) give me my QMap and i can do anything with this :CCCC
so there is a some trick to instert data to QMap in QList ((( ?
please help

---

Added after 23 minutes:

Ok sorry for spam
I do this with QVector

this->MapVector[Index].insert(QPoint(x,y), someIndex);

this->MapVector[Index].insert(QPoint(x,y), someIndex);

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[lanz]

You can do it with QList too

this->MapList[0].insert (QPoint (x, y), 1);

this->MapList[0].insert (QPoint (x, y), 1);

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or even

this->MapList[0][QPoint(x,y)] = 1;

this->MapList[0][QPoint(x,y)] = 1;

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[jesse_mark]

As Lanz said, you can use [ ] for insertion, but not .at(), use "at" when you want to retrieve data as it very fast. but u can not use it for insertion.