指向 unsigned char 数组的 unsigned char 指针

Question

I'm trying to make an array of unsigned char's and make a pointer which points to the first position of the array but I keep getting an error. This is my code as well as the error:

void initBuffer
{
      unsigned char buffer[size];
      unsigned char *ptr;
      ptr = &buffer;
}

I suspect it's a very simple type error buy I'm new to C and not sure how to fix it.

Answer 1

The type of &buffer is unsigned char (*)[size] .

The type of ptr is unsigned char * .

Those two types are not the same. Just as the compiler tells you.

Assuming you want to make ptr point to the first elements of buffer then you need to use &buffer[0] which has the correct type. And that's what plain buffer will decay to:

ptr = buffer;

Answer 2

I made a minor change to the code you provided, ptr = &buffer[0];

#include <stdio.h>
int main() {
      unsigned char buffer[] = {'A','B','C','D'};
      unsigned char *ptr;
      ptr = &buffer[0];    // ptr, points to first element of array
      for(int i=0; i<4; i++)
          printf("%c", ptr[i]);
      return 0;
}