Once you have information stored in a variable, what are you going to do with it? As we have seen, you can echo it to a web page. You also can manipulate the information with operators. Here are examples of mathematical operations in PHP:
$b = $a + 3; $c = $a - 5; $b = $b * 5; $d = $b / $c; |
In addition to the basic assignment operator (=), there is a string-concatenation operator (.=) and combination assignment/mathematical operators. Here are some examples:
$string1 = "super"; $string2 = "star"; $string1 .= $string2; // $string 1 now equals "superstar" $name = "Stephen"; $name .= " Crampton"; // note the space; name now equals "Stephen Crampton" $c = 5; $c += 1; // result is $c + 2, or 6 $c -= -1; // result is $c - (- 1), or 7 $x = 5; $x *= $c; // result is $x * $c, or 35 $y = 70; $y /= $x // result is $y / $x, or 2 |
There also are simple increment/decrement operators, which are essentially shorthand ways of adding or subtracting one from a number:
$a = 5;
$a++; // $a has been incremented by 1, and now equals 6
$a--; // $a has been decremented by 1, and now equals 5
$b = 5 * $a++; // Note that the incrementing happens after the evaluation:
// First, $b is calculated to be 25. Then, $a is
// incremented to become 6
//
// If you want $a to be incremented first, put the ++ in front of it
// as follows:
$b = 5 * ++$a; // $a incremented to 7; $b becomes 35
$c = 100;
$c -= ++$b + $a++; // $b becomes 36; $c is calculated to be
// 100 - ( 36 + 7 ); finally, $a becomes 8
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