what is masking in c?

[vikramdattrana]

i know that it is something related with the bit fields and the i know about the bit operators....but what actually is the masking??

[weaknessforcats]

A mask is a bit pattern. Suppose you have this pattern of bits in an unsigned char:

11001010

and you want to see if bit 3 is set (that's the 4th bit from the right). So you use a mask:

00001000

and AND the mask with the bit pattern:


11001010
00001000
------------
00001000

If the result of the AND matches the mask, then the 4th bit is set.

And remember: There is no money in bit-fiddling :)

[Savage]

A mask is a bit pattern. Suppose you have this pattern of bits in an unsigned char:

11001010

and you want to see if bit 3 is set (that's the 4th bit from the right). So you use a mask:

00001000

and AND the mask with the bit pattern:


11001010
00001000
------------
00001000

If the result of the AND matches the mask, then the 4th bit is set.

And remember: There is no money in bit-fiddling :)

Sayed in simple English:

Mask used with bit operator & is used to pull out from memory word bits that u wish to use.

Mask used with bit operator |(OR) is used to set bit or bits in state 1,independent from they previous state.Thats why we use with it mask that in does positions have value of 1 and in all other value of 0

e.g

0100101010111001
|
0000000000110001
---------------------------
0100101010111001

Mask used with operator ^ has nearly the same tautology as a | operator.Only differance is that when using ^ 1 and 1 will result in 0 and it's well suited to test equality of two different memory words
e.g

0000100111000011
^
0101010010110111
---------------------------
0101111000010100

And last bit operator resembles negation (~)

Savage