C++重新解释_cast

发布于 2024-10-15 06:46:59 字数 309 浏览 6 评论 0原文

在运行该程序时：

#include <iostream>
int main()
{
char *name = "abc";
int i = reinterpret_cast<int>(name);
std::cout<<i<<std::endl;
return 0;
}

我得到以下输出：

4202656

这个数字代表什么？是内存地址吗？但是，内存地址是什么？ “abc”不是作为字符数组存储在内存中吗？

谢谢。

原文

In running this program:

#include <iostream>
int main()
{
char *name = "abc";
int i = reinterpret_cast<int>(name);
std::cout<<i<<std::endl;
return 0;
}

I got the following output:

4202656

What does this number represent? Is it a memory address? But, memory address of what? Isn't "abc" stored as an array of characters in memory?

Thanks.

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暖伴 2024-10-22 06:46:59

它是未定义的。 sizeof(int) 可能不等于 sizeof(char*)。我不确定严格的别名规则是否也适用于此。

但实际上，假设它们的大小确实相等（大多数 32 位平台），则 4202656 将表示数组中第一个字符的地址。我会这样更干净地做到这一点：

#include <iostream>
int main()
{
   const char *name = "abc"; // Notice the const. Constant string literals cannot be modified.
   std::cout << static_cast<const void*>(name) << std::endl;
}

It is undefined. sizeof(int) might not be equal to sizeof(char*). I'm not sure if strict aliasing rules apply here as well.

In practice however, assuming their sizes are indeed equal (most 32-bit platforms), 4202656 would represent the address of the first character in the array. I would do this more cleanly this way:

#include <iostream>
int main()
{
   const char *name = "abc"; // Notice the const. Constant string literals cannot be modified.
   std::cout << static_cast<const void*>(name) << std::endl;
}

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