Interpreting hex values?

Question

This might be very basic or even silly to experts here but I wanted to get my head around this. Most of the times I generally write hex values like this in C:

unsigned int a = 0xFFFF1232;

Let's say I am trying to extract the first and last 16-bits then I can simply do:

unsigned short high = a >> 16; // Gives me 0xFFFF
unsigned short low = a & 0x0000FFFF; // Gives me 0x00001232 which is then stored as 0x1232

In some of the code I am reading I have come across the following:

unsigned short high = a >> 16; 
unsigned short low = a & 0xFFFF; 

I have two questions

• When you are ANDing a 32-bit value with a mask, why do people write 0xFFFF instead of 0x0000FFFF? Is it to keep it compact?
• Is it always safe to write 0x0000FFFF as 0xFFFF? Is it interpreted differently in any context?

Answer 1

They're completely synonymous. Leaving out the leading zeros makes it a little more readable.