如何在 C++ 对象中初始化数组
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How to initialize an array in C++ objects
提问by Quade2002
After reading How to initialize an array in C, in particular:
阅读如何在 C 中初始化数组后，特别是：
Don't overlook the obvious solution, though:
int myArray[10] = { 5, 5, 5, 5, 5, 5, 5, 5, 5, 5 };
但是，不要忽视明显的解决方案：
int myArray[10] = { 5, 5, 5, 5, 5, 5, 5, 5, 5, 5 };
I tried something like this:
我试过这样的事情：
#include <iostream>
class Something {
private:
int myArray[10];
public:
Something() {
myArray[10] = { 5, 5, 5, 5, 5, 5, 5, 5, 5, 5 };
}
int ShowThingy(int what) {
return myArray[what];
}
~Something() {}
};
int main () {
Something Thing;
std::cerr << Thing.ShowThingy(3);
}
And I get:
我得到：
..\src\Something.cpp: In constructor 'Something::Something()':
..\src\Something.cpp:10:48: error: cannot convert '<brace-enclosed initializer list>' to 'int' in assignment
The obvious in this case is not so obvious. I really would like the initiation of my array to be more dynamic as well.
在这种情况下，显而易见的事情并不那么明显。我真的希望我的数组的启动也更加动态。
I tired:
我累了：
private:
int * myArray;
public:
Something() {
myArray = new int [10];
myArray = { 5, 5, 5, 5, 5, 5, 5, 5, 5, 5 };
}
This looked funky to me to, and so to the compiler:
这对我来说看起来很时髦，对编译器来说也是如此：
..\src\Something.cpp: In constructor 'Something::Something()':
..\src\Something.cpp:11:44: error: cannot convert '<brace-enclosed initializer list>' to 'int*' in assignment
This also did not work:
这也不起作用：
private:
int myArray[10] = { 5, 5, 5, 5, 5, 5, 5, 5, 5, 5 };
with:
和：
..\src\Something.cpp:6:20: error: a brace-enclosed initializer is not allowed here before '{' token
..\src\Something.cpp:6:51: sorry, unimplemented: non-static data member initializers
..\src\Something.cpp:6:51: error: 'constexpr' needed for in-class initialization of static data member 'myArray' of non-integral type
I have been doing really good and learning what does not work, but not so good learning what does work.
我一直做得很好，学习什么不起作用，但不太好学习什么起作用。
So, how do I used initialization lists {value, value, value} for an array inside a class?
那么，我如何为类中的数组使用初始化列表 {value, value, value} ？
I have been trying to figure out how to do this for some time now and am very stuck, I have a number of these kinds of lists I need to make for my app.
一段时间以来，我一直试图弄清楚如何做到这一点，但我很困惑，我需要为我的应用程序制作许多此类列表。
回答by Praetorian
You need to initialize the array in the constructor initialization list
需要在构造函数初始化列表中初始化数组
#include <iostream>
class Something {
private:
int myArray[10];
public:
Something()
: myArray { 5, 5, 5, 5, 5, 5, 5, 5, 5, 5 }
{
}
int ShowThingy(int what) {
return myArray[what];
}
~Something() {}
};
int main () {
Something Thing;
std::cerr << Thing.ShowThingy(3);
}
..\src\Something.cpp:6:51: sorry, unimplemented: non-static data member initializers
..\src\Something.cpp:6:51: 抱歉，未实现：非静态数据成员初始值设定项
C++11 also adds supports for inline initialization of non-static member variables, but as the above error message states, your compiler has not implemented this yet.
C++11 还添加了对非静态成员变量的内联初始化的支持，但正如上面的错误消息所述，您的编译器尚未实现这一点。
回答by derekerdmann
Unless I'm mistaken, the initializer list is only allowed for when the variable is initialized during declaration - hence the name. You can't assign an initializer list to a variable, as you're trying to do in most of your examples.
除非我弄错了，只有在声明期间初始化变量时才允许使用初始化器列表 - 因此得名。您不能像在大多数示例中那样将初始化列表分配给变量。
In your last example, you're trying to add static initialization to a non-static member. If you want the array to be a static member of the class, you could try something like this:
在上一个示例中，您尝试向非静态成员添加静态初始化。如果你想让数组成为类的静态成员，你可以尝试这样的事情：
class Derp {
private:
static int myArray[10];
}
Derp::myArray[] = { 5, 5, 5, 5, 5, 5, 5, 5, 5, 5 };
If you want to add a class member, you could try making the static array constand copy it into the member array in the constructor.
如果要添加类成员，可以尝试制作静态数组const并将其复制到构造函数中的成员数组中。
