Question

我试图理解为什么两者都：

#include <unistd.h>

int main()
{
    char buffer[8] = "Hello 
";
    write(1, buffer, 7);
    return 0;
}

和Cookies政策，

#include <unistd.h> 

int main()
{
   char buffer[8];
   char *ptr = buffer;
   ptr = "Hello 
";
   write(1, ptr, 7);
   return 0;
}

成功将“Hello”输出到控制台，但

#include <unistd.h> 

int main()
{
   char buffer[8];
   char *ptr = buffer;
   ptr = "Hello 
";
   write(1, buffer, 7);
   retrun 0;
}

当我期望这三者基本上相同时，它不会（而是输出胡言乱语）。

I m guessing there is something fundamentally wrong in my underst和Cookies政策，ing of the relationship between pointers 和Cookies政策， arrays in c ...

Answer 1

您在这里混淆了几个不同的、无关的问题：

 char buffer[8];      // You re allocating 8 bytes: OK
 char *ptr = buffer;  // You re aliasing "ptr" to "&buffer[0]": OK
 ptr = "Hello 
";    // Now you re ASSIGNING ptr to a completely DIFFERENT address
 write(1, buffer, 7); // You never actually assigned any data to buffer

假设您这样做了：

 char buffer[8];      // Allocate 8 bytes
 char *ptr = buffer;  // Aliasing "ptr" to "&buffer[0]"
 strcpy(ptr, "Hello 
"); // Now you ve actually assigned data
 write(1, buffer, 7); /. You should no longer see "garbage" ;)

换句话说，这个问题不是“指针与数组” ，而是“正确初始化您所指向的任何内容”。

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