如何从指针获取数组的长度? [英] How to get the length of an array from a pointer?

问题描述

我无法找到指针数组的长度.假设我有:

I'm having trouble finding the length of an pointer array. Let's say I have:

char array[40] = "hello"; // size 40
int length =  sizeof array / sizeof array[0]; // no problem returns 40

//如何仅通过指向数组中第一个元素的指针来获取数组的长度?

//How do I get the length of the array with only a pointer to the first element in that array?

 char* pchar = array;

//如果

std::strlen(pchar); // this returns the length of 5... i want length 40

//如果

int count = 0;
while(true)
{
  if(*(pchar + count) == '\0') // returns 5...
    break;
   count++;
}

如何让它仅从指向数组中第一个元素的指针返回长度为 40?
我发现我可以做到这一点.

How do I get it to return length 40 just from a pointer to the first element in the array?
I found that I can do this.

int count = 0;
    while(true)
    {
      if(*(pchar + count) == '\0' && *(pchar + count + 1) != '\0') 
             break;

       count++;
    }

这返回 39，这很好，但我觉得这在某些情况下可能会出错.

This returns 39, this is good but I feel like this can be buggy in some situations.

推荐答案

恐怕不行.您需要将数组的长度传递给需要它的任何人.或者您可以使用 std::array 或 std::vector 或类似的，它们会自行跟踪长度.

You can't, I'm afraid. You need to pass the length of the array to anyone who needs it. Or you can use a std::array or std::vector or similar, which keep track of the length themselves.

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