类中的数组初始化

Question

I try to create a date class and would like to set array in it as:

class Date {
private:
    int day;
    int month;
    int year;
    int daysPerMonth[12] = {31,28,31,30,31,30,31,31,30,31,30,31};
};

Compiler gives an error that it is forbidden to use array like this. How can I do this?

Answer 1

Array initialisation for class members (in-place, or with initializer lists) is a new feature in C++11. If you have compiler that supports the updated language, you can use the following syntax:

class Date {
private:
    int daysPerMonth[12] {31,28,31,30,31,30,31,31,30,31,30,31};
};

However, in the case of days per month it might be a little pointless (assuming you are only supporting the Gregorian calendar), because that kind of thing tends to be declared as static const (these values should never change and do not need multiple instances), which would allow the data to be initialised easily using language features that predate C++11. eg

// In the header
class Date {
private:
    static int const daysPerMonth[12];
};

// And in the implementation file
int const Date::daysPerMonth[12] = {31,28,31,30,31,30,31,31,30,31,30,31};