Memory access by address

  • hey bros;
    I have a program to access the variables by their addresses and this is my code:

    float f;
    int t;

    QHash <int,int*> hash;

    qDebug()<<"t1="<<t1; //t1= 34

    qDebug()<<"f="<<f; //f=7.94536e-43 !!!!!!

    why this code is not working? and how can i fix that?
    Actually the objective of this code is to indexing every variable with any type (int, float, structure, Boolean, .. ) by an integer number. Hashing is used to achieve this goal.
    Thanks a lot

  • If i use QVariant like below:

    @QHash <int,QVariant*> hash;
    and i insert the same values into it, i encounter this error:

    : error: C2664: 'QHash<Key,T>::insert' : cannot convert parameter 2 from 'int *' to 'QVariant *const &'
    T=QVariant *

    But if i use the previous code and retrieve the address as below:
    qDebug()<<“f=”<<f; //f=456.987@

    everything will be OK.

  • Hi,
    Better to not use pointers to your variables for this. A QVariant will use the same amount of memory space as the variable it will point to. So, the QHash should have an <int, QVariant> not the pointer. Then add the variable to the QVariant via a constructor or other variant function and you should be able to convert any variable into that QHash. Even mix them if needed.

  • hey Jeroentje@home
    thanks for your reply But could you please make an example of your plan?

  • Lifetime Qt Champion

    Jeroentje@home meant that you should follow koahnig's example

    QHash<int, QVariant> hash;
    float fInput= 1.2
    hash.insert(1, fInput);
    float myFloat = hash.value(1).toFloat();

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