assignment-expr := logical-or-expr &= assignment-expr | 
    logical-or-expr and_eq assignment-expr

The and_eq operator is an assignment operator that performs bitwise and. It is equivalent to logical-or-expr = logical-or-expr & assignment-expr except that logical-or-expr is evaluated only once. The keyword and_eq is interchangeable with the &= token.

Example

unsigned bitmask = 0xFFFF;
bitmask &= ~0x7E; // bitmask becomes 0xFF81.

See Also

bitand, expression, or_eq, xor_eq, Chapter 3, <ciso646>