CODEWITHSUNDEEP
c++
R4de
R4de

Reputation: 77

invalid conversion from ‘const int*’ to ‘int*’ in template function

class A{
    private:
        T x;
    public:
        A():x(0){}
        A(T x1):x(x1){}

        void printInfo(const T& a){
            cout<<"Succes1"<<endl;
        }
};

class B{
    private:
        int x;
        A<int*> var;
    public:
        B():x(0){}
        B(int x1):x(x1){}

        void printInfo(const int * a){
            var.printInfo(a);
        }
};

The probelms is with 

void printInfo(const int * a){
    var.printInfo(a);
}

It gives an error, saying invalid conversion from ‘const int*’ to ‘int*’

but works with int *a or int *const a

Shouldn't void printInfo in class A look like

void printInfo(const int* a)

Is this correct?

cont int *p, //pointer to constant int

int* const p //constant pointer to int

if thats the case there should be error with 

printInfo(int* const a)

not with

printInfo(const int * a)

Upvotes: 1

Views: 425

Answers (2)

Thomas
Thomas

Reputation: 5138

Shouldn't void printInfo in class A look like

void printInfo(const int* a)

Is this correct?

No, the problem ist that you declare var as A<int*> in B, so A's 

void printInfo(const T& a);

is really

void printInfo( int* const& a);

and not

void printInfo( int const* & a);

So, for the call in B to work you need to declare var as A<int const*>. See compiling version here.

Upvotes: 1

eerorika
eerorika

Reputation: 238311

void printInfo(const int * a){

Shouldn't void printInfo in class B look like

void printInfo(const int* a)

Is this correct?

Both are equivalent. In many cases, whitespace is not syntactically relevant.

cont int *p, //pointer to constant int

int* const p //constant pointer to int

These are correct.

if thats the case there should be error with

printInfo(int* const a)

not with

printInfo(const int * a)

The error should be when you attempt to implicitly convert a pointer to const into pointer to non-const.

Upvotes: 0

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