C + +: How to turn an int into 4 bytes?

As you all know, an int or unsigned int is made up of 4 bytes, (The Learning Guide for C/s + +, chapter 3rd, section 3.2.3: Memory view of variables)

For example

int n = sizeof (int); N is 4

It is also clear to see in memory, that 4 bytes is there, (the "C + + Learning Guide", Appendix: VC2008 Debugging Method)

But the question is: How do you turn the code into 4 bytes?

Method 1:memcpy

This method is violent and unscientific. Let's try it first.

unsigned int a = 0x12345678;

unsigned char buf[4];

memcpy (buf, &a, 4);

Observe the value of the 4 elements of the BUF array, is not 0x78 0x56 0x34 0x12 (well, small end, this is the flaw, we want the result is actually buf[0]=0x12 buf[1]=0x34 buf[2]=0x56 buf[4]=0x78)

Method 2: Formal Methods ("C + + Learning Guide", chapter 6th, section 6.8)

Buf[0] = a >> 24;

BUF[1] = a >> 16;

BUF[2] = a >> 8;

BUF[3] = A;

Use your VC to see if it is right for you. Look directly in the debug state, stop printf.

No thanks, it's supposed to be!

C + +: How to turn an int into 4 bytes?