php - 引用-这个符号在PHP中是什么意思？

Question

这是什么？

这是有关PHP语法的不时出现的问题的集合。这也是社区Wiki，因此邀请所有人参与维护此列表。

为什么是这样？

过去很难找到有关运算符和其他语法标记的问题。¹
主要思想是链接到Stack Overflow上的现有问题，因此我们更容易引用它们，而不必复制PHP手册中的内容。

注意：自2013年1月起，堆栈溢出does support special characters。只需用引号将搜索字词括起来，例如[php] "==" vs "==="

我该怎么办？

如果有人因提出这样的问题而将您指向此处，请在下面找到特定的语法。 PHP manual的链接页面以及链接的问题可能会回答您的问题。如果是这样，建议您增加答案。此列表不能代替其他人提供的帮助。

名单

如果您的特定令牌未在下面列出，则可以在List of Parser Tokens中找到它。



& Bitwise Operators或References


What does it mean to start a PHP function with an ampersand?
Understanding PHP & (ampersand, bitwise and) operator
PHP "&" operator
Difference between & and && in PHP
What does "&" mean here in PHP?
What does "&" mean in this case?
What does the "&" sign mean in PHP?
What does this signature mean (&) in PHP?
How does the "&" operator work in a PHP function?
What does & in &2 mean in PHP?
When should I use a bitwise operator?
Is there ever a need to use ampersand in front of an object?（＆$）




=& References


Reference assignment operator in PHP, =&
What do the "=&" and "&=" operators in PHP mean?
What do the '&=' and '=&' operators do?
What does =& mean in PHP?




&= Bitwise Operators


What do the "=&" and "&=" operators in PHP mean?
What do the '&=' and '=&' operators do?




&& Logical Operators


'AND' vs '&&' as operator
Difference between & and && in PHP
Is there any difference between "and" and "&&" operators in PHP?
PHP - and / or keywords




% Arithmetic Operators


What does the percent sign mean in PHP?
What is the PHP operator % and how do I use it in real-world examples?




!! Logical Operators


Double not (!!) operator in PHP




@ Error Control Operators


What is the use of the @ symbol in PHP?
'At' symbol before variable name in PHP: @$_POST
PHP functions and @functions
Should I use @ in my PHP code?
What does @ mean in PHP?




?: Ternary Operator


What are the PHP operators "?" and ":" called and what do they do?
?: operator (the 'Elvis operator') in PHP
Where can I read about conditionals done with "?" and ":" (colon)?
Using PHP 5.3 ?: operator




?? Null Coalesce Operator（自PHP 7起）


C#'s null coalescing operator (??) in PHP




?string
?int
?array
?bool
?float Nullable return type declaration（自PHP 7.1起）


Nullable return type declaration




: Alternative syntax for control structures，Ternary Operator


What is ":" in PHP?
What does ":" mean in PHP?




:: Scope Resolution Operator


What do two colons mean in PHP?
What's the meaning of the PHP token name T_PAAMAYIM_NEKUDOTAYIM?
What's the difference between :: (double colon) and -> (arrow) in PHP?
What exactly are late static bindings in PHP?
static::staticFunctionName()
Unexpected T_PAAMAYIM_NEKUDOTAYIM, expecting T_NS_Separator




\ Namespaces


Backslash in PHP -- what does it mean?
What does a \ (backslash) do in PHP (5.3+)?




-> Classes And Objects


What is the "->" PHP operator called and how do you say it when reading code out loud?
Where do we use the object operator "->" in PHP?
What's the difference between :: (double colon) and -> (arrow) in PHP?
What does the PHP syntax $var1->$var2 mean?
What does "->" mean/refer to in PHP?




=> Arrays


What does "=>" mean in PHP?
Use of => in PHP
What does $k => $v in foreach($ex as $k=>$v) mean?




^ Bitwise Operators


How does the bitwise operator XOR ('^') work?
What does ^ mean in PHP?




>> Bitwise Operators


What does >> mean in PHP?




<< Bitwise Operators


Strange print behaviour in PHP?




<<< Heredoc or Nowdoc


What does <<<END mean in PHP?
PHP expression <<<EOB
In PHP, what does "<<<" represent?
Using <<<CON in PHP
What's this kind of syntax in PHP?




= Assignment Operators


The 3 different equals




== Comparison Operators


How do the PHP equality (== double equals) and identity (=== triple equals) comparison operators differ?
PHP != and == operators
The 3 different equals
Type-juggling and (strict) greater/lesser-than comparisons in PHP




=== Comparison Operators


What does "===" mean?
How do the PHP equality (== double equals) and identity (=== triple equals) comparison operators differ?
The 3 different equals
Type-juggling and (strict) greater/lesser-than comparisons in PHP




!== Comparison Operators


What does !== comparison operator in PHP mean?
Is there a difference between !== and != in PHP?




!= Comparison Operators


PHP != and == operators
Is there a difference between !== and != in PHP?
comparing, !== versus !=
What is the difference between <> and !=




<> Comparison Operators


PHP operator <>
PHP's <> operator
What is the difference between <> and !=
Type-juggling and (strict) greater/lesser-than comparisons in PHP




<=> Comparison Operators（自PHP 7.0起）


Spaceship (three way comparison) operator




| Bitwise Operators


What is the difference between the | and || operators?
What Does Using A Single Pipe '|' In A Function Argument Do?




|| Logical Operators


What is the difference between the | and || operators?
PHP - and / or keywords
What exactly does || mean?
The behaviour of the or operator in PHP




~ Bitwise Operators


What does this ~ operator mean here?




+ Arithmetic Operators，Array Operators


+ operator for array in PHP?




+=和-= Assignment Operators


What is += used for?
What does `$page -= 1` in my PHP document mean?




++和-- Incrementing/Decrementing Operators


Understanding Incrementing
Answer below




.= Assignment Operators


What is the difference between .= and += in PHP?
To understand a line of PHP




. String Operators


Difference between period and comma when concatenating with echo versus return?
What does a . (dot) do in PHP?




, Function Arguments


Difference between period and comma when concatenating with echo versus return?


, Variable Declarations


What do commas mean in a variable declaration?




$$ Variable Variables


What does $$ (dollar dollar or double dollar) mean in PHP?
what is "$$" in PHP
$function() and $$variable




` Execution Operator


What are the backticks `` called?




<?= Short Open Tags


What does this symbol mean in PHP <?=
What does '<?=' mean in PHP?
What does <?= mean?




[] Arrays（自PHP 5.4起的简短语法）


PHP arrays... What is/are the meaning(s) of an empty bracket?
What is the meaning of []
Php array_push() vs myArray[]
What does [] mean when reading from a PHP array?
Shorthand for arrays: literal $var = [] empty array




<? Opening and Closing tags


Are PHP short tags acceptable to use?




... Argument unpacking（自PHP 5.6起）



** Exponentiation（自PHP 5.6起）



# One-line shell-style comment


Can I use hashes for comments in PHP?




:? Nullable return types


php method argument type hinting with question mark (?type)

Answer 1

Incrementing / Decrementing Operators

++增量运算符

--减量运算符

Example    Name              Effect
---------------------------------------------------------------------
++$a       Pre-increment     Increments $a by one, then returns $a.
$a++       Post-increment    Returns $a, then increments $a by one.
--$a       Pre-decrement     Decrements $a by one, then returns $a.
$a--       Post-decrement    Returns $a, then decrements $a by one.

这些可以在变量之前或之后。

如果放在变量之前，则先对变量执行递增/递减操作，然后返回结果。如果将变量放在变量之后，则首先返回变量，然后执行增量/减量操作。

例如：

$apples = 10;
for ($i = 0; $i < 10; ++$i) {
    echo 'I have ' . $apples-- . " apples. I just ate one.\n";
}

Live example

在上述情况下，使用++$i是因为它更快。 $i++将具有相同的结果。

预增量要快一点，因为它实际上是递增变量，然后“返回”结果。后增量创建一个特殊变量，在其中复制第一个变量的值，只有在使用第一个变量之后，才将其值替换为第二个变量。

但是，必须使用$apples--，因为首先要显示当前的苹果数量，然后再从中减去一个。

您还可以在PHP中增加字母：

$i = "a";
while ($i < "c") {
    echo $i++;
}

达到z后，接着是aa，依此类推。


  请注意，字符变量可以递增但不能递减，即使如此，仅支持纯ASCII字符（a-z和A-Z）。




堆栈溢出帖子：


Understanding Incrementing