What Is an Operation?

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This section describes what is an operation - a process that takes one or two operands and returns a result based on certain processing rule represented by the operator.

What Is an Operation? An operation is a process that takes one or two operands and returns a result based on certain processing rule represented by the operator. PHP supports most types of operations used in other programming languages:

1. Bitwise Operations: and ($a & $b), or ($a | $b), xor ($a ^ $b), not (~ $a), shift left ($a << $s), and shift right ($a >> $s).

2. Incrementing/Decrementing Operations: pre-increment (++$a), post-increment ($a++), pre-decrement (--$a), and post-decrement ($a--).

3. Arithmetic Operations: negation (-$a), addition ($a + $b), subtraction ($a - $b), multiplication ($a * $b), division ($a / $b), and modulus ($a % $b).

4. Comparison Operations: equal ($a == $b), identical ($a === $b), not equal ($a != $b, $a <> $b), not identical ($a !== $b), less than ($a < $b), greater than ($a > $b), less than or equal ($a <= $b), and greater than or equal ($a >= $b).

5. Logical Operations: and ($a and $b, $a && $b), or ($a or $b, $a || $b), xor ($a xor $b), and not (!$a).

6. String Operation: concatenation ($a . %b).

7. Assignment Operations: assignment ($a = %b), addition with assignment ($a += $b), subtraction with assignment ($a -= $b), multiplication with assignment ($a *= $b), division with assignment ($a /= $b), modulus with assignment ($a %= $b), and concatenation with assignment ($a .= %b).

To help us understand different types of operations, I wrote the following PHP script, OperationTest.php:

<?php # OperationTest.php
# Copyright (c) 2005 by Dr. Herong Yang. http://www.herongyang.com/
#
   print "\n Bitwise Operations:\n";
   print "    0x00FF & 0x3210: " . (0x00FF & 0x3210) . "\n";
   print "    0x0001 | 0x0010: " . (0x0001 | 0x0010) . "\n";
   print "    0x0001 << 4: " . (0x0001 << 4) . "\n";
   print "    0x0100 >> 4: " . (0x0100 >> 4) . "\n";

   print "\n Incrementing/Decrementing Operations:\n";
   $a = 10; $b = ++$a * 2;
   print "    \$b = ++\$a * 2: $a, $b\n";
   $a = 10; $b = $a++ * 2;
   print "    \$b = \$a++ *2: $a, $b\n";
   
   print "\n Arithmetic Operations:\n";
   $a = 9; $b = 4;
   print "    \$a * \$b: ". $a * $b . "\n";
   print "    \$a * \$b: ". $a / $b . "\n";
   print "    \$a * \$b: ". $a % $b . "\n";

   print "\n Comparison Operations:\n";
   $a = 9; $b = 4;
   print "    \$a > \$b: ". ($a > $b) . "\n";
   print "    \$a < \$b: ". ($a < $b) . "\n";

   print "\n Logical Operations:\n";
   $a = 9; $b = 4; $c = 1;
   print "    \$a > \$b && \$b > \$c: ". ($a > $b && $b > $c) . "\n";

   print "\n String Operation:\n";
   $name = "Herong"; $greeting = "Hello";
   print "    \$greeting . \$name: ". ($greeting . $name) . "\n";

   print "\n Assignment Operation:\n";
   print "    \$name=\"Herong\": ". ($name="Herong") . "\n";
?>

If you run this sample script, you should get:

 Bitwise Operations:
    0x00FF & 0x3210: 16
    0x0001 | 0x0010: 17
    0x0001 << 4: 16
    0x0100 >> 4: 16

 Incrementing/Decrementing Operations:
    $b = ++$a * 2: 11, 22
    $b = $a++ *2: 11, 20

 Arithmetic Operations:
    $a * $b: 36
    $a * $b: 2.25
    $a * $b: 1

 Comparison Operations:
    $a > $b: 1
    $a < $b:

 Logical Operations:
    $a > $b && $b > $c: 1

 String Operation:
    $greeting . $name: HelloHerong

 Assignment Operation:
    $name="Herong": Herong

Last update: 2005.

Sections in This Chapter

What Is an Expression?

What Is an Operation?

Precedence of Operations

Data Type Automatic Conversion