使用assign() 是初始化我的C++ 结构向量的好方法吗? [英] Is using assign() a good way to initialise my C++ vector of structs?

问题描述

结构

struct Vanish
{
  int iCount;
  int iRow;
};

我定义了一个 Vanish 的 std::vector 作为我的类的成员，并希望像这样在构造函数中初始化它:

I defined a std::vector of Vanish as a member of my class, and want to initialise it in the constructor like this:

class BigClass
{
  public:
    BigClass();
  private:
    std::vector<Vanish> tovanish;
};

void BigClass::BigClass()
{
  Vanish empty = {0,0};
  tovanish.assign(MAX_VANISH, empty);
}

有没有更好的方法，或者这被认为可以?

Is there a better way, or is this considered OK?

推荐答案

最好在构造函数的初始化列表中这样做:

It is better to do that in the constructor's initializer list:

BigClass::BigClass()
: tovanish(MAX_VANISH)
{

}

那样，您将避免可能的向量重新分配.请注意，vector 的构造函数将对它的元素进行值初始化.Vanish 中 int 成员的值初始化只是将它们归零.

That way, you'll avoid possible vector reallocations. Note that you vector's constructor will value-initialize its elements. Value-initialization of the int members in Vanish just zeroes them.

请注意，在 C++11 中，使用统一初始化可以轻松指定其他值:

Note that in C++11, using uniform-initialization you could specify other values easily:

BigClass::BigClass()
: tovanish(MAX_VANISH, {42, 24})
{

}

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