通过赋值运算符在索引处插入std :: vector [英] Inserting into a std::vector at an index via the assignment operator

问题描述

我是C ++的新手，并且很好奇这是否是插入std :: vector的首选方式

I'm new to C++ and am curious if this is the preferred way of inserting into a std::vector

std::vector<Object_I_madeup> myVector;

   void setAt(int x, Object_I_madeup o)
        {
            myVector[x] = o;

        } // set the array location at x  to be o.

我之所以问，是因为我看到了很多有关使用 push_back 的信息，或者令人困惑的 insert()的信息.这种类似Java的方式有效吗?我宁愿那样做...

I ask because I see a lot of things about using push_back,or the highly confusing insert(). Is this Java-like way valid? I'd much rather do that...

推荐答案

myVector[x] = o;

只有 x<myVector.size().否则，它将调用undefined-behavior，因为在这种情况下，它将尝试访问向量边界之外的元素.

It is well-defined only if x < myVector.size(). Otherwise, it invokes undefined-behavior, because in that case it attempts to access an element out of the bound of the vector.

如果您想确保它也检查出站访问权限，请使用 at() 为:

If you want to make sure that it checks for out-of-bound-access also, then use at() as:

myVector.at(x) = o;

现在，如果 x> = myVector.size()，它将抛出 std :: out_of_range 异常.因此，您必须将此代码放入 try-catch 块中！它们之间的区别将在此处进行详细讨论.

Now it will throw std::out_of_range exception if x >= myVector.size(). So you have to put this code in try-catch block! The difference between them is discussed at great detail here.

• 为什么使用"vector.at(x)"比"vector [x]"更好在C ++中?

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