?
7-1.
$a + $b | $a $b. | |
$a - $b | $b $a. | |
$a * $b | $a $b. | |
$a / $b | $a $b. | |
$a % $b | $a $b. |
("/") ( ) - ( ). , .
B -- (".").
$a = "Hello ";$b = $a. "World!"; // $b = "Hello World!"
"=". ""("equal to"). . ( ).
. "$a = 3", 3. :
$a = ($b = 4) + 5; // $a 9, $b 4." ", , . :
$a = 3; $a += 5; // $a 8, : $a = $a + 5;
$b = "Hello ";
$b.= "There!"; // $b "Hello There!", $b = $b. "There!";
( )
.
Table 7-2.
$a & $b | , $a $b. * : $a=5; /* 0101 */ $b=12; /* 1100 */ $c=$a & $b; /* $c 4 (0100) */ | |
$a | $b | , $a $b. * : $a=5; /* 0101 */ $b=12; /* 1100 */ $c=$a|$b; /* $c (1101) */ | |
~ $a | _ $a () * : $a=5; /* 0101 */ ~ $a /* $a x (1010) */ |
7-3.
$a and $b | , $a $b. | |
$a or $b | , $a $b. | |
$a xor $b | , $a $b, . | |
! $a | , $a. | |
$a && $b | , $a $b. | |
$a || $b | , $a $b. |
"and" "or" - . (. )