// We need a period (.) in preg_match regular expression to matches any single character
echo preg_match("/b.d/", "bud") . "\n"; // returns true (1)
echo preg_match("/b.d/", "bid") . "\n"; // returns true (1)
echo preg_match("/b.d/", "bed") . "\n"; // returns true (1)
echo preg_match("/b.d/", "b d") . "\n"; // returns true (1)
echo preg_match("/b.d/", "bat") . "\n"; // returns false (0)
echo preg_match("/b.d/", "bd") . "\n"; // returns false (0)
echo preg_match("/b.d/", "bead") . "\n"; // returns false (0)
echo preg_match("/ab.dx/", "ab.dx") . "\n"; // returns false (1)
/*
run:
1
1
1
1
0
0
0
1
*/