VS compiling error when passing arguments to c++ constructor

Question

I'm trying to pass two arguments to a constructor:

class CTest1
{
public:
    CTest1(const int i8BitImageID, const int i256BitImageID) : m_i8BitImageID(i8BitImageID), m_i256BitImageID(i256BitImageID) {};
private:
    int m_i8BitImageID;
    int m_i256BitImageID;
};

#define BITMAP_1_ID 1
#define BITMAP_2_ID 2

class CTest2
{
public:
    CTest1 test1(BITMAP_1_ID, BITMAP_2_ID); // Compile error here
};

When I compile this (using Visual Studio 2017), the line where I declare "test1" results in a "C2059: syntax error: 'constant'" error. I've tried with an without "const" in the definition of the constructor.

Thanks!

Consider learning from a [good C++ book](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list). — Algirdas Preidžius, May 09 '18 at 15:28
Unfortunately, the compiler error is quite misleading this time. — user202729, May 09 '18 at 15:31
Possible duplicate of [VC++6 error C2059: syntax error : 'constant'](https://stackoverflow.com/questions/4519035/vc6-error-c2059-syntax-error-constant) — user202729, May 09 '18 at 15:34
Compiler sees this as function declaration of name `test1` that returns `CTest1` and does not accept constants there. Hense the error. @songyuanyao already explained how to fix it — Slava, May 09 '18 at 15:34

songyuanyao · Accepted Answer · 2018-05-09T15:32:41.787

4

Default member initializer only works with brace or equals initializer. e.g.

class CTest2
{
public:
    CTest1 test1 = CTest1(BITMAP_1_ID, BITMAP_2_ID);
    CTest1 test2 {BITMAP_1_ID, BITMAP_2_ID};
};

Or you could use member initializer list.

class CTest2
{
public:
    CTest2() : test1(BITMAP_1_ID, BITMAP_2_ID) {}
    CTest1 test1;
};

edited May 09 '18 at 15:32

answered May 09 '18 at 15:29

songyuanyao

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VS compiling error when passing arguments to c++ constructor

1 Answers1