Errors, bugs, questions - page 1087

[A100]

The abbreviated notation of the postfix operator++ does not compile when an explicit conversion of a base class pointer to a derived

class A {
};

class B : public A {
public:
        void    operator++( int ) {}
        void    operator++()      {}
};

void f( A* a )
{
        ((B *)a).operator++( 0 ); //нормально
        ((B *)a).operator++();    //нормально
        ++((B *)a);               //нормально
        ((B *)a)++;               //ошибка
}

[A100]

At least the compiler should warn that a.f() is not const

class A {
public:
        int f() { return ( 1 ); }
};

class B {
public:
                B( const A *aa ) : a( aa ) {}
        int g() { return ( a.f() ); } //должно быть предупреждение, поскольку a.f() не const
        const A *a;
};

[Ilyas]

A100:
At least the compiler should warn that a.f() is not const

Thank you for your diligence, both errors have been corrected.

[A100]

mql5:
Thanks for the heads up, both errors have been corrected.

Only the last one is not technically an error - only a warning should be. It is only an error if

class B {
public:
        A * const a;
};

But in the templates. I'll give you examples later.

[A100]

Here too - it's not clear.

class A {
public:
};

void ex1( const A* &t1, const A* &t2 )
{
        const A* t = t1;
        t1 = t2;
        t2 = t;
}

void OnStart()
{
    const A *a1 = new A(), *a2 = new A();
    Print( "Было :" a1, " ", a2 ); // Было :1 2
    ex1( a1, a2 );
    Print( "Стало:"  a1, " ", a2 ); // Стало:2 1
    delete( a1 );
    delete( a2 );
}

everything works correctly, but if you add the intermediate function ex2(...)

void ex2( const A* &t1, const A* &t2 ) { ex1( t1, t2 ); }

void OnStart()
{
    сonst A *a1 = new A(), *a2 = new A();
    Print( "Было: ", a1, " ",  a2 ); // Было :1 2
    ex2( a1, a2 );
    Print( "Стало:",  a1, " ",  a2 ); // Cтало:2 2           <-----
    delete( a1 ); delete( a2 );
}

The result is different. What did ex2(...) do ? - just passed the pointers by reference on

Please take a look at

[Ilyas]

A100:

Here too - it's not clear.

everything works correctly, but if you add the intermediate function ex2(...)

The result is different. What did ex2(...) do ? - just passed the pointers by reference on

Please take a look at

Thanks, language optimizer error, fixed.

[Aleksey Rodionov]

It's not the first time, but it's the only time you get such photos when uploading, which means you have to set some criteria (you probably have a certain size).
). They are displayed normally everywhere else. Please tell me what's wrong.

[A100]

An unnecessary compilation error occurs if the macro uses a result type conversion and the return value is then not used (sometimes it is needed, sometimes it is not)

int g( int x ) { return ( x ); }

#define  F( X )    (long)g( X )

void OnStart()
{
        int f = F( 0 ); //нормально
        F( 0 );         //ошибка компиляции
}

[Test Account]

A100:
An unnecessary compilation error occurs if a macro uses a result type conversion, and the return value is not subsequently used (sometimes it is needed, sometimes not)

This has nothing to do with the use of defines.

A simple define equivalent will also give the same error

(long)g(0);

'(long)' - expression has no effect

P.S. Now there will be a vorning here.

[Andrey Vasiliev]

After recompiling the indicator, the "array out of range" error started to occur when working with dynamic arrays.

It didn't occur before. What to do?