如何找到数组的长度? [英] How do I find the length of an array?

问题描述

有没有办法找到一个数组有多少个值?检测我是否已经到达数组的末尾也可以.

Is there a way to find how many values an array has? Detecting whether or not I've reached the end of an array would also work.

推荐答案

如果你的意思是一个 C 风格的数组，那么你可以这样做:

If you mean a C-style array, then you can do something like:

int a[7];
std::cout << "Length of array = " << (sizeof(a)/sizeof(*a)) << std::endl;

这不适用于指针(即它不适用于以下任一情况):

This doesn't work on pointers (i.e. it won't work for either of the following):

int *p = new int[7];
std::cout << "Length of array = " << (sizeof(p)/sizeof(*p)) << std::endl;

或:

void func(int *p)
{
    std::cout << "Length of array = " << (sizeof(p)/sizeof(*p)) << std::endl;
}

int a[7];
func(a);

在 C++ 中，如果你想要这种行为，那么你应该使用容器类；可能是 std::vector.

In C++, if you want this kind of behavior, then you should be using a container class; probably std::vector.

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