bitwise and
The bitwise AND operator in C++ is a single ampersand, &, used between two other integer expressions. Bitwise AND operates on each bit position of the surrounding expressions independently, according to this rule: if both input bits are 1, the resulting output is 1, otherwise the output is 0. Another way of expressing this is:
0 & 0 == 0
0 & 1 == 0
1 & 0 == 0
1 & 1 == 1
One of the most common uses of bitwise AND is to select a particular bit (or bits) from an integer value, often called masking. For example, if you wanted to access the least significant bit in a variable x, and store the bit in another variable y, you could use the following code:
int x = 5; // binary: 101
int y = x & 1; // now y == 1
x = 4; // binary: 100
y = x & 1; // now y == 0
