What is automatic alignment when allocating space?

aoaksm

When asking the teacher's linked list, the teacher mentioned that when allocating space, it was not simple addition, and automatic alignment or something.

pretendersam

For example, when you format a hard disk, you usually have the file system option and the size of the smallest allocation unit. If the minimum allocation unit is 16 K, it means that you have created a new file, even if you only wrote , The system will also allocate 16 K of hard disk space for you.

The memory is the same.In order to facilitate memory management, the smallest allocation unit is generally selected, such as 32 bit.If you declare a char-type variable, it originally thought that it only took up 1 byte of space, in fact it took up 4 bytes.

zjzhizi

struct A
{
 char a;
 int b;
};
struct B
{
 int a;
 int b;
};
sizeof (A) == sizeof (B) == 8
char is padded to int (default 4 bytes)

mowenjx

A data access optimization technology for the compiler, which can be set by compiler instructions

星语空翼

This is also called data alignment, and it is explained in a section in "Windows Core Programming".