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c++qtconstantsconst-correctnessqlist
kiriloff
kiriloff

Reputation: 26333

Qt QList C3892: cannot assign to a variable that is const

I have const correctness issue with QList.

I have a method getValue whose signature i cannot change returning const double and here

double vs = MinInput->getValue(0, 0);

vs is const.

I would like to build QList with results from this method and i get error C3892.

Since my list is a QList, cannot add const double (?)

Code is like that 

    QList<double> minmax;
    for (int i = 0; i < 2*(3+othercutoffs_var_len) ; i++  )
        minmax.append( 0.0 );


    QSP< const VarInterface<double> > MinInput = ctx.getInputVar<double>(ctx.input(Id::fromString(QL1s("Min")))[0] );
    const double vs = MinInput->getValue(0, 0);
    minmax.at(0) = vs;

and this very last line of code is getting me into trouble. (other errors when filling the list with other such const doubles)

signature for getValue is like that

const TYPE & VarData<TYPE>::getValue( uint r, uint c ) const

Upvotes: 0

Views: 2309

Answers (2)

Amartel
Amartel

Reputation: 4286

I guess the correct code would be:

minmax[0] = vs;

Update:

QList::at returns const reference, which cannot be modified.

Upvotes: 3

PrisonMonkeys
PrisonMonkeys

Reputation: 1229

QList::at(int i) is a getter function. It returns a const reference, and you cannot assign anything to it.

Use QList::operator[](int i) or QList::replace(int i, const & T value) to set the value at position i.

Upvotes: 2

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