PHP | 运算符

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运算符

操作符用于对某些值执行操作。换句话说，我们可以将运算符描述为接受一些值，对它们执行一些操作并给出结果的东西。从示例中可以看出，表达式‘+’中的“1 + 2 = 3”是一个运算符。它取两个值1和2，对它们执行加法运算得到3。与任何其他编程语言一样，PHP也支持各种类型的操作，比如算术操作(加法、减法等)、逻辑操作(和，或等)、递增/递减操作等。因此，PHP为我们提供了许多操作符来对各种操作数、变量或值执行此类操作。这些操作符只是执行各种类型操作所需的符号。以下是不同组别的操作员:

  • 算术运算符
  • 逻辑或关系运算符
  • 比较运算符
  • 条件运算符或三元运算符
  • 赋值运算符
  • 太空船操作员(PHP 7中介绍)
  • 数组运算符
  • 递增/递减运算符
  • 字符串操作符

现在让我们详细了解这些操作符:

算术运算符

算术运算符用于执行简单的数学运算，如加法、减法、乘法等。下面是一系列算术运算符，以及PHP提供的语法和操作:

OperatorNameSyntaxOperation
+加号$x + $y和操作数
–减号$x – $y差操作数
*乘号$x * $y乘操作数
/除号$x / $y除操作数
**取幂$x ** $y取幂操作数
%取模$x % $y取模操作数

注意:PHP 5.6中已经介绍了求幂。

例子

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<?php
 
// variable 1
$x = 29;
 
// variable 2
$y = 4;
 
// some arithmetic operations on
// these two variables
echo ($x + $y), "\n";
echo($x - $y), "\n";
echo($x * $y), "\n";
echo($x / $y), "\n";
echo($x % $y), "\n";
 
?>

输出

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3
4
5
33
25
116
7.25
1

逻辑或关系运算符

这些基本用于操作条件语句和表达式。条件语句是基于条件的。同样，条件可以满足也可以不满足，因此条件语句的结果可以是真，也可以是假。下面是PHP提供的逻辑运算符以及语法和操作:

OperatorNameSyntaxOperation
andLogical AND$x and $y 如果两个操作数都为真，则为真
orLogical OR$x or $y 如果操作数之一为真，则为真，否则为假
xorLogical XOR$x xor $y 如果操作数之一为真，则为真;如果两个操作数都为真，则为假
&&Logical AND$x && $y 如果两个操作数都为真，则为真
||Logical OR$x || $y 如果操作数之一为真，则为真，否则为假
!Logical NOT!$x 如果$x为假，则为真

例子

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<?php
 
$x = 50;
$y = 30;
 
if ($x == 50 and $y == 30)
echo "and Success \n";
 
if ($x == 50 or $y == 20)
echo "or Success \n";
 
if ($x == 50 xor $y == 20)
echo "xor Success \n";
 
if ($x == 50 && $y == 30)
echo "&& Success \n";
 
if ($x == 50 || $y == 20)
echo "|| Success \n";
 
if (!$z)
echo "! Success \n";
 
?>

输出

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and Success
or Success
xor Success
&& Success
|| Success
! Success

比较运算符

这些操作符用于比较两个元素并以布尔形式输出结果。下面是比较运算符以及PHP提供的语法和操作:

OperatorNameSyntaxOperation
==Equal To$x == $yReturns True if both the operands are equal
!=Not Equal To$x != $yReturns True if both the operands are not equal
<>Not Equal To$x != $yReturns True if both the operands are unequal
===Identical$x === $yReturns True if both the operands are equal and are of the same type
!==Not Identical$x == $yReturns True if both the operands are unequal and are of different types
<Less Than$x < $yReturns True if $x is less than $y
>Greater Than$x > $yReturns True if $x is greater than $y
<=Less Than or Equal To$x <= $yReturns True if $x is less than or equal to $y
>=Greater Than or Equal To$x >= $yReturns True if $x is greater than or equal to $y

例子

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<?php
 
$a = 80;
$b = 50;
$c = "80";
 
// Here var_dump function has been used to
// display structured information. We will learn
// about this function in complete details in further
// articles.
var_dump($a == $c) + "\n";
var_dump($a != $b) + "\n";
var_dump($a <> $b) + "\n";
var_dump($a === $c) + "\n";
var_dump($a !== $c) + "\n";
var_dump($a < $b) + "\n";
var_dump($a > $b) + "\n";
var_dump($a <= $b) + "\n";
var_dump($a >= $b);
 
?>

输出

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9
bool(true)
bool(true)
bool(true)
bool(false)
bool(true)
bool(false)
bool(true)
bool(false)
bool(true)

条件运算符或三元运算符

这些运算符用于比较两个值，并根据结果是真还是假，同时获取两个结果。这些也是我们将在关于决策的文章中读到的if…else语句的简写符号。

语法

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$var = (condition)? value1 : value2;

在这里，条件值要么为真，要么为假。如果条件求值为True，那么value1将被分配给变量$var，否则value2将被分配给它。

OperatorNameOperation
?:TernaryIf condition is true ? then $x : or else $y. This means that if condition is true then left result of the colon is accepted otherwise the result on right.

例子

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<?php
 
$x = -12;
 
echo ($x > 0) ? 'The number is positive' : 'The number is negative';
 
?>

输出

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The number is negative

赋值运算符

这些操作符用于为不同的变量赋值，不管是否有中间操作。下面是赋值运算符以及PHP提供的语法和操作:

OperatorNameSyntaxOperation
=Assign$x = $yOperand on the left obtains the value of the operand on right
+=Add then Assign$x += $ySimple Addition same as $x = $x + $y
-=Subtract then Assign$x -= $ySimple subtraction same as $x = $x – $y
*=Multiply then Assign$x *= $ySimple product same as $x = $x * $y
/=Divide then Assign (quotient)$x /= $ySimple division same as $x = $x / $y
%=Divide then Assign (remainder)$x %= $ySimple division same as $x = $x % $y

例子

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<?php
 
// simple assign operator
$y = 75;
echo $y, "\n";
 
// add then assign operator
$y = 100;
$y += 200;
echo $y, "\n";
 
// subtract then assign operator
$y = 70;
$y -= 10;
echo $y, "\n";
 
// multiply then assign operator
$y = 30;
$y *= 20;
echo $y, "\n";
 
// Divide then assign(quotient) operator
$y = 100;
$y /= 5;
echo $y, "\n";
 
// Divide then assign(remainder) operator
$y = 50;
$y %= 5;
echo $y;
 
?>

输出

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75
300
60
600
20
0

数组运算符

这些运算符用于数组。这里是数组操作符以及PHP提供的语法和操作:

OperatorNameSyntaxOperation
+Union$x + $yUnion of both i.e., $x and $y
==Equality$x == $yReturns true if both has same key-value pair
!=Inequality$x != $yReturs True if both are unequal
===Identity$x === $yReturns True if both has same key-value pair in the same order and of same type
!==Non-Identity$x !== $yReturns True if both are not identical to each other
<>Inequality$x <> $yReturns True if both are unequal

例子

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<?php
 
$x = array("k" => "Car", "l" => "Bike");
$y = array("a" => "Train", "b" => "Plane");
 
var_dump($x + $y);
var_dump($x == $y) + "\n";
var_dump($x != $y) + "\n";
var_dump($x <> $y) + "\n";
var_dump($x === $y) + "\n";
var_dump($x !== $y) + "\n";
 
?>

输出

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array(4) {
  ["k"]=>
  string(3) "Car"
  ["l"]=>
  string(4) "Bike"
  ["a"]=>
  string(5) "Train"
  ["b"]=>
  string(5) "Plane"
}
bool(false)
bool(true)
bool(true)
bool(false)
bool(true)

递增/递减运算符

这些操作符称为一元操作符，因为它在单个操作数上工作。它们用于递增或递减值。

OperatorNameSyntaxOperation
++Pre-Increment$x++First returns $x, then increment it by one
—Pre-Decrement$x–First returns $x, then decrement it by one
++Post-Increment++$xFirst increments $x by one, then return $x
++Post-Increment++$xFirst increments $x by one, then return $x
—Post-Decrement–$xFirst decrements $x by one, then return $x

例子

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<?php
 
$x = 2;
echo ++$x, " First increments then prints \n";
echo $x, "\n";
 
$x = 2;
echo $x++, " First prints then increments \n";
echo $x, "\n";
 
$x = 2;
echo --$x, " First decrements then prints \n";
echo $x, "\n";
 
$x = 2;
echo $x--, " First prints then decrements \n";
echo $x;
 
?>

输出

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3 First increments then prints
3
2 First prints then increments
3
1 First decrements then prints
1
2 First prints then decrements
1

字符串操作符

这些是通过字符串实现的。

OperatorNameSyntaxOperation
.Concatenation$x.$yConcatenated $x and $y
.=Concatenation and assignment$x.=$yFirst concatenates then assigns, same as $x = $x.$y

例子

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<?php
 
$x = "sky8g";
$y = "for";
$z = "sky8g!!!";
echo $x . $y . $z, "\n";
 
$x .= $y . $z;
echo $x;
 
?>

输出

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sky8gforsky8g!!!
sky8gforsky8g!!!

太空船操作员(PHP 7中介绍)

PHP 7引入了一种新的操作符，称为飞船操作符()。这些操作符用于比较值，但它不返回布尔结果，而是返回整数值。如果两个操作数都相等，则返回0。如果正确的操作数更大，则返回-1。如果左操作数更大，则返回1。下表详细展示了它的工作原理:

OperatorSyntaxOperation
$x < $y$x <=> $yIdentical to -1 (right is greater)
$x > $y$x <=> $yIdentical to 1 (left is greater)
$x <= $y$x <=> $yIdentical to -1 (right is greater) or identical to 0 (if both are equal)
$x >= $y$x <=> $yIdentical to 1 (if left is greater) or identical to 0 (if both are equal)
$x == $y$x <=> $yIdentical to 0 (both are equal)
$x != $y$x <=> $yNot Identical to 0

例子

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<?php
 
$x = 50;
$y = 50;
$z = 25;
 
echo $x <=> $y;
echo "\n";
 
echo $x <=> $z;
echo "\n";
 
echo $z <=> $y;
echo "\n";
 
// We can do the same for Strings
$x = "Ram";
$y = "Krishna";
 
echo $x <=> $y;
echo "\n";
 
echo $x <=> $y;
echo "\n";
 
echo $y <=> $x;
 
?>

输出

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0
1
-1
1
1
-1

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