传递指针参数（函数内部给指针赋值）示例

#include <stdio.h>

unsigned char *ptr = NULL;
unsigned char num = 3;

static void fun(unsigned char **mem)
{
	*mem = &num;	
} 

int main()
{
	fun(&ptr);
	printf("%d \n", *ptr);
	
	return 0;
}