... as 11 0 in binary, and 5 is represented as 10 1. If we evaluate 6 & 5: echo( 6 // 11 0 & 5 // 10 1 ); // equals 4 = 10 0 The most significant bit of both 6 and 5 is set to 1. Therefore, ... probably never need it in PHP. The bitwise operators are summarized in the table below. Operator Description Example & And 11 (10 11 binary) & 13 (11 01 binary) ... have three files, named file1 .php, file2 .php and file3 .php, which contain code we want to include in another PHP pahe. With include, we can do this: for ($i = 1; $i <= 3; ++$i) { include("file"...