Reference What does this symbol mean in PHP

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What is this  This is a collection of questions that come up every now and then about syntax in PHP  This is also a Community Wiki  so everyone is invited to participate in maintaining this list  Why is this  It used to be hard to find questions about operators and other syntax tokens    The main idea is to have links to existing questions on Stack Overflow  so it s easier for us to reference them  not to copy over content from the PHP Manual  Note  Since January 2013  Stack Overflow does support special characters  Just surround the search terms by quotes  e g   php   quot    quot  vs  quot     quot  What should I do here  If you have been pointed here by someone because you have asked such a question  please find the particular syntax below  The linked pages to the PHP manual along with the linked questions will likely answer your question then  If so  you are encouraged to upvote the answer  This list is not meant as a substitute to the help others provided  The List If your particular token is not listed below  you might find it in the List of Parser Tokens    amp  Bitwise Operators or References  What does it mean to start a PHP function with an ampersand  Understanding PHP  amp   ampersand  bitwise and  operator PHP  quot  amp  quot  operator Difference between  amp  and  amp  amp  in PHP What does  quot  amp  quot  mean here in PHP  What does  quot  amp  quot  mean in this case  What does the  quot  amp  quot  sign mean in PHP  What does this signature mean   amp   in PHP  How does the  quot  amp  quot  operator work in a PHP function  What does  amp  in  amp 2 mean in PHP  When should I use a bitwise operator  Is there ever a need to use ampersand in front of an object    amp        amp  References  Reference assignment operator in PHP    amp  What do the  quot   amp  quot  and  quot  amp   quot  operators in PHP mean  What do the   39  amp    39  and   39   amp   39  operators do  What does   amp  mean in PHP     amp   Bitwise Operators  What do the  quot   amp  quot  and  quot  amp   quot  operators in PHP mean  What do the   39  amp    39  and   39   amp   39  operators do     amp  amp  Logical Operators    39 AND  39  vs   39  amp  amp   39  as operator Difference between  amp  and  amp  amp  in PHP Is there any difference between  quot and quot  and  quot  amp  amp  quot  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    39 At  39  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  quot   quot  and  quot   quot  called and what do they do     operator  the   39 Elvis operator  39   in PHP Where can I read about conditionals done with  quot   quot  and  quot   quot   colon   Using PHP 5 3    operator      Null Coalesce Operator  since PHP 7   C   39 s null coalescing operator      in PHP    string  int  array  bool  float Nullable return type declaration  since PHP 7 1   Nullable return type declaration php method argument type hinting with question mark   type      Alternative syntax for control structures  Ternary Operator  What is  quot   quot  in PHP  What does  quot   quot  mean in PHP       Scope Resolution Operator  What do two colons mean in PHP  What  39 s the meaning of the PHP token name T PAAMAYIM NEKUDOTAYIM  What  39 s the difference between     double colon  and - gt   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      - gt  Classes And Objects  What is the  quot - gt  quot  PHP operator called  Where do we use the object operator  quot - gt  quot  in PHP  What  39 s the difference between     double colon  and - gt   arrow  in PHP  What does the PHP syntax  var1- gt  var2 mean  What does  quot - gt  quot  mean refer to in PHP      gt  Arrays  What does  quot   gt  quot  mean in PHP  Use of   gt  in PHP What does  k   gt   v in foreach  ex as  k  gt  v  mean      Bitwise Operators  How does the bitwise operator XOR    39    39   work  What does   mean in PHP     gt  gt  Bitwise Operators  What does  gt  gt  mean in PHP     lt  lt  Bitwise Operators  Strange print behaviour in PHP     lt  lt  lt  Heredoc or Nowdoc  What does  lt  lt  lt END mean in PHP  PHP expression  lt  lt  lt EOB In PHP  what does  quot  lt  lt  lt  quot  represent  Using  lt  lt  lt CON in PHP What  39 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  quot     quot  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  lt  gt  and       lt  gt  Comparison Operators  PHP operator  lt  gt  PHP  39 s  lt  gt  operator What is the difference between  lt  gt  and    Type-juggling and  strict  greater lesser-than comparisons in PHP    lt   gt  Comparison Operators  since PHP 7 0   Spaceship  three way comparison  operator     Bitwise Operators  What is the difference between the   and    operators  What Does Using A Single Pipe   39    39  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       and -  Assignment Operators  What is    used for  What does   page -  1  in my PHP document mean       and -- 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  quot    quot  in PHP  function   and   variable     Execution Operator  What are the backticks    called     lt    Short Open Tags  What does this symbol mean in PHP  lt    What does   39  lt     39  mean in PHP  What does  lt    mean       Arrays  short syntax since PHP 5 4   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    lt   Opening and Closing tags  Are PHP short tags acceptable to use        Argument unpacking  since PHP 5 6      Exponentiation  since PHP 5 6     One-line shell-style comment  Can I use hashes for comments in PHP     - gt  NullSafe Operator Calls  since PHP 8 0   What does this symbol mean  quot  - gt  quot  in php  within an object or null value

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An overview of operators in PHP   Logical Operators    a  amp  amp   b   TRUE if both  a and  b are TRUE   a     b   TRUE if either  a or  b is TRUE   a xor  b   TRUE if either  a or  b is TRUE  but not both     a   TRUE if  a is not TRUE   a and  b   TRUE if both  a and  b are TRUE   a or  b   TRUE if either  a or  b is TRUE    Comparison operators    a     b   TRUE if  a is equal to  b after type juggling   a      b     TRUE if  a is equal to  b  and they are of the same type   a     b   TRUE if  a is not equal to  b after type juggling   a  lt  gt   b   TRUE if  a is not equal to  b after type juggling   a      b     TRUE if  a is not equal to  b  or they are not of the same type   a  lt   b   TRUE if  a is strictly less than  b   a  gt   b   TRUE if  a is strictly greater than  b   a  lt    b   TRUE if  a is less than or equal to  b   a  gt    b   TRUE if  a is greater than or equal to  b   a  lt   gt   b   An integer less than  equal to  or greater than zero when  a is respectively less than  equal to  or greater than  b  Available as of PHP 7   a    b    c   if  a return  b else return  c  ternary operator   a     c   Same as  a    a    c  null coalescing operator - requires PHP gt  7    Arithmetic Operators   - a   Opposite of  a   a    b   Sum of  a and  b   a -  b   Difference of  a and  b   a    b   Product of  a and  b   a    b   Quotient of  a and  b   a    b   Remainder of  a divided by  b   a     b   Result of raising  a to the  b th power  introduced in PHP 5 6    Incrementing Decrementing Operators      a   Increments  a by one  then returns  a   a     Returns  a  then increments  a by one  -- a   Decrements  a by one  then returns  a   a--   Returns  a  then decrements  a by one    Bitwise Operators    a  amp   b   Bits that are set in both  a and  b are set   a    b   Bits that are set in either  a or  b are set   a    b   Bits that are set in  a or  b but not both are set     a   Bits that are set in  a are not set  and vice versa   a  lt  lt   b   Shift the bits of  a  b steps to the left  each step means  quot multiply by two quot    a  gt  gt   b   Shift the bits of  a  b steps to the right  each step means  quot divide by two quot     String Operators    a    b   Concatenation of  a and  b    Array Operators    a    b   Union of  a and  b   a     b   TRUE if  a and  b have the same key value pairs   a      b   TRUE if  a and  b have the same key value pairs in the same order and of the same types   a     b   TRUE if  a is not equal to  b   a  lt  gt   b   TRUE if  a is not equal to  b   a      b   TRUE if  a is not identical to  b    Assignment Operators    a    b   The value of  b is assigned to  a  a     b   Same as  a    a    b  a -   b   Same as  a    a -  b   a    b   Same as  a    a    b  a     b   Same as  a    a    b  a     b   Same as  a    a    b    a    b   Same as  a    a     b  a     b   Same as  a    a    b  a  amp    b   Same as  a    a  amp   b  a     b   Same as  a    a    b  a     b   Same as  a    a    b  a  lt  lt    b   Same as  a    a  lt  lt   b  a  gt  gt    b   Same as  a    a  gt  gt   b  a      b   The value of  b is assigned to  a if  a is null or not defined  null coalescing assignment operator - requires PHP gt  7 4    Note and operator and or operator have lower precedence than assignment operator    This means that  a   true and false  is equivalent to   a   true  and false  In most cases you will probably want to use  amp  amp  and     which behave in a way known from languages like C  Java or JavaScript

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Three DOTS as Splat Operator        since PHP 5 6   PHP has an operator        Three dots  which is referred as Splat Operator  It is used to pass arbitrary number of parameters in a function and this type of function is called Variadic Functions  Let   s take examples to use of        Three dots       Example 1     lt  php function calculateNumbers     params        total   0      foreach  params as  v            total    total    v            return  total     echo calculateNumbers 10  20  30  40  50      Output 150   gt    Each arguments of calculateNumbers   function pass through  params as an array when use          There are many different ways to use         operator  Below some examples      Example 2     lt  php function calculateNumbers  no1   no2   no3   no4   no5        total    no1    no2    no3    no4    no5      return  total      numbers   array 10  20  30  40  50   echo calculateNumbers     numbers      Output 150   gt       Example 3     lt  php function calculateNumbers     params        total   0      foreach  params as  v            total    total    v            return  total     no1   70   numbers   array 10  20  30  40  50   echo calculateNumbers  no1      numbers      Output 220   gt       Example 4     lt  php function calculateNumbers     params        total   0      foreach  params as  v            total    total    v            return  total      numbers1   array 10  20  30  40  50    numbers2   array 100  200  300  400  500   echo calculateNumbers     numbers1      numbers2      Output 1650    gt

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- gt  NullSafe Operator Added in PHP 8 0 It s the NullSafe Operator  it returns null in case you try to invoke functions or get values from null  Nullsafe operator can be chained and can be used both on the methods and properties   objDrive   null   drive    objDrive - gt func - gt getDriver   - gt value    return null  drive    objDrive- gt func- gt getDriver  - gt value     Error  Trying to get property  func  of non-object  Nullsafe operator doesn t work with array keys   drive  admin   - gt getDriver   - gt value   Warning  Trying to access array offset on value of type null   drive        drive  admin   - gt getAddress   - gt value   Warning  Undefined array key  quot admin quot

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Alias for gettext      The underscore character     as in     is an alias to the gettext   function

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is used for check equality without considering variable data-type     is used for check equality for both the variable value and data-type Example  a   5  if   a    5   - will evaluate to true  if   a     5   - will evaluate to true  because while comparing this both value PHP internally convert that string value into integer and then compare both values  if   a     5  - will evaluate to true  if   a      5   - will evaluate to false  because value is 5  but this value 5 is not an integer

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Spaceship Operator  lt   gt   Added in PHP 7  Examples for  lt   gt  Spaceship operator  PHP 7  Source  PHP Manual   Integers  Floats  Strings  Arrays  amp  objects for Three-way comparison of variables     Integers echo 10  lt   gt  10     0 echo 10  lt   gt  20     -1 echo 20  lt   gt  10     1     Floats echo 1 5  lt   gt  1 5     0 echo 1 5  lt   gt  2 5     -1 echo 2 5  lt   gt  1 5     1     Strings echo  quot a quot   lt   gt   quot a quot      0 echo  quot a quot   lt   gt   quot b quot      -1 echo  quot b quot   lt   gt   quot a quot      1    Comparison is case-sensitive echo  quot B quot   lt   gt   quot a quot      -1  echo  quot a quot   lt   gt   quot aa quot      -1 echo  quot zz quot   lt   gt   quot aa quot      1     Arrays echo     lt   gt         0 echo  1  2  3   lt   gt   1  2  3      0 echo  1  2  3   lt   gt         1 echo  1  2  3   lt   gt   1  2  1      1 echo  1  2  3   lt   gt   1  2  4      -1     Objects  a    object    quot a quot    gt   quot b quot      b    object    quot a quot    gt   quot b quot     echo  a  lt   gt   b     0   a    object    quot a quot    gt   quot b quot      b    object    quot a quot    gt   quot c quot     echo  a  lt   gt   b     -1   a    object    quot a quot    gt   quot c quot      b    object    quot a quot    gt   quot b quot     echo  a  lt   gt   b     1     only values are compared  a    object    quot a quot    gt   quot b quot      b    object    quot b quot    gt   quot b quot     echo  a  lt   gt   b     1

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Bitwise Operator  What is a bit  A bit is a representation of 1 or 0  Basically OFF 0  and ON 1   What is a byte  A byte is made up of 8 bits and the highest value of a byte is 255  which would mean every bit is set  We will look at why a byte s maximum value is 255   -------------------------------------------        1 Byte   8 bits                      -------------------------------------------  Place Value   128  64  32  16  8  4  2  1       -------------------------------------------   This representation of 1 Byte  1   2   4   8   16   32   64   128   255  1 Byte    A few examples for better understanding  The  AND  operator      a    9   b   10  echo  a  amp   b    This would output the number 8  Why  Well let s see using our table example   -------------------------------------------        1 Byte   8 bits                      -------------------------------------------  Place Value   128  64  32  16  8  4  2  1       -------------------------------------------         a        0   0   0   0  1  0  0  1      -------------------------------------------         b        0   0   0   0  1  0  1  0  -------------------------------------------          amp          0   0   0   0  1  0  0  0  -------------------------------------------    So you can see from the table the only bit they share together is the 8 bit   Second example   a    36   b   103  echo  a  amp   b     This would output the number 36   a   00100100  b   01100111   The two shared bits are 32 and 4  which when added together return 36   The  Or  operator      a    9   b   10  echo  a    b    This would output the number 11  Why   -------------------------------------------        1 Byte   8 bits                      -------------------------------------------  Place Value   128  64  32  16  8  4  2  1       -------------------------------------------         a        0   0   0   0  1  0  0  1      -------------------------------------------         b        0   0   0   0  1  0  1  0  -------------------------------------------                   0   0   0   0  1  0  1  1  -------------------------------------------   You will notice that we have 3 bits set  in the 8  2  and 1 columns  Add those up  8 2 1 11

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Curly braces   Blocks - curly braces no curly braces  Curly braces in string in PHP PHP curly braces in array notation   And some words about last post   x 4     d      it works  x 4     d      it works   echo  x 4      it works  echo  x 4      it works   x      e      it works  x      e      does not work   x    1  2      it works  x    1  2      does not work  echo    x 4        it works echo    x 4        does not work  echo    x 4        it works echo    x 4        it works

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Type Operators  instanceof is used to determine whether a PHP variable is an instantiated object of a certain class    lt  php class mclass     class sclass      a   new mclass  var dump  a instanceof mclass   var dump  a instanceof sclass     The above example will output   bool true  bool false    Reason  Above Example  a is a object of the mclass so use only a mclass data not instance of with the sclass  Example with inheritance   lt  php  class pclass      class childclass extends pclass       a   new childclass   var dump  a instanceof childclass    var dump  a instanceof pclass     The above example will output   bool true  bool true    Example with Clone   lt  php  class cloneable       a   new cloneable   b   clone  a   var dump  a instanceof cloneable    var dump  b instanceof cloneable     The above example will output   bool true  bool true

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Question   What does   amp   mean here in PHP   PHP   amp   operator  Makes life more easier once we get used to it   check example below carefully    amp  usually checks bits that are set in both  a and  b are set      have you even noticed how these calls works       error reporting E ERROR   E WARNING   E PARSE       error reporting E ERROR   E WARNING   E PARSE   E NOTICE       error reporting E ALL  amp   E NOTICE       error reporting E ALL     So behind all above is game of bitwise operator and bits   One usefull case of these is easy configurations like give below  so a single integer field can store thousands of combos for you    Most people have already read the docs but didn t reliase the real world use case of these bitwise operators   Example That you  ll love   lt  php  class Config           our constants must be 1 2 4 8 16 32 64     so on     const TYPE CAT 1      const TYPE DOG 2      const TYPE LION 4      const TYPE RAT 8      const TYPE BIRD 16      const TYPE ALL 31       private  config       public function   construct  config            this- gt config  config           if  this- gt is Config  TYPE CAT                echo  cat                      if  this- gt is Config  TYPE DOG                echo  dog                      if  this- gt is Config  TYPE RAT                echo  rat                      if  this- gt is Config  TYPE LION                echo  lion                      if  this- gt is Config  TYPE BIRD                echo  bird                      echo   n              private function is  value           return  this- gt config  amp   value           new Config Config  TYPE ALL      cat dog rat lion bird new Config Config  TYPE BIRD     bird new Config Config  TYPE BIRD   Config  TYPE DOG     dog bird new Config Config  TYPE ALL  amp   Config  TYPE DOG  amp   Config  TYPE CAT     rat lion bird

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PHP Strings  PHP Strings can be specified in four ways not just two ways   1  Single Quote Strings     string    This is my string      print This is my string   2  Double Quote Strings     str    string     string    This is my  str      print This is my string   3  Heredoc     string    lt  lt  lt EOD This is my string EOD     print This is my string   4  Nowdoc  since PHP 5 3 0      string    lt  lt  lt  END OF STRING      This is my string  END OF STRING     print This is my string

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Null coalescing operator       This operator has been added in PHP 7 0 for the common case of needing to use a ternary operator in conjunction with isset    It returns its first operand if it exists and is not NULL  otherwise it returns its second operand    lt  php    Fetches the value of   GET  user   and returns  nobody     if it does not exist   username     GET  user       nobody      This is equivalent to   username   isset   GET  user        GET  user      nobody       Coalescing can be chained  this will return the first    defined value out of   GET  user      POST  user    and     nobody    username     GET  user        POST  user       nobody     gt

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Incrementing   Decrementing Operators     increment operator  -- decrement operator  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    These can go before or after the variable   If put before the variable  the increment decrement operation is done to the variable first then the result is returned  If put after the variable  the variable is first returned  then the increment decrement operation is done   For example    apples   10  for   i   0   i  lt  10     i        echo  I have      apples--     apples  I just ate one  n       Live example  In the case above    i is used  since it is faster   i   would have the same results   Pre-increment is a little bit faster because it really increments the variable and after that  returns  the result  Post-increment creates a special variable  copies there the value of the first variable and only after the first variable is used  replaces its value with second s   However  you must use  apples--  since first  you want to display the current number of apples  and then you want to subtract one from it   You can also increment letters in PHP    i    a   while   i  lt   c         echo  i        Once z is reached aa is next  and so on      Note that character variables can be incremented but not decremented and even so only plain ASCII characters  a-z and A-Z  are supported      Stack Overflow Posts    Understanding Incrementing

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Syntax Name Description     x    y Equality true if x and y have the same key value pairs   x    y Inequality true if x is not equal to y   x     y Identity true if x and y have the same key value pairsin the same order and of the same types   x     y Non-identity true if x is not identical to y     x Pre-increment Increments x by one  then returns x   x   Post-increment Returns x  then increments x by one   --x Pre-decrement Decrements x by one  then returns x   x-- Post-decrement Returns x  then decrements x by one   x and y And true if both x and y are true  If x 6  y 3 then x  lt  10 and y  gt  1  returns true   x  amp  amp  y And true if both x and y are true  If x 6  y 3 then x  lt  10  amp  amp  y  gt  1  returns true   x or y Or true if any of x or y are true  If x 6  y 3 then x  lt  10 or y  gt  10  returns true   x    y Or true if any of x or y are true  If x 6  y 3 then x  lt  3    y  gt  1  returns true   a   b Concatenation Concatenate two strings   quot Hi quot     quot Ha quot

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Magic constants  Although these are not just symbols but important part of this token family  There are eight magical constants that change depending on where they are used     LINE    The current line number of the file     FILE    The full path and filename of the file  If used inside an include  the name of the included file is returned  Since PHP 4 0 2    FILE   always contains an absolute path with symlinks resolved whereas in older versions it contained relative path under some circumstances     DIR    The directory of the file  If used inside an include  the directory of the included file is returned  This is equivalent to dirname   FILE     This directory name does not have a trailing slash unless it is the root directory   Added in PHP 5 3 0      FUNCTION    The function name   Added in PHP 4 3 0  As of PHP 5 this constant returns the function name as it was declared  case-sensitive   In PHP 4 its value is always lowercased     CLASS    The class name   Added in PHP 4 3 0  As of PHP 5 this constant returns the class name as it was declared  case-sensitive   In PHP 4 its value is always lowercased  The class name includes the namespace it was declared in  e g  Foo Bar   Note that as of PHP 5 4   CLASS   works also in traits  When used in a trait method    CLASS   is the name of the class the trait is used in     TRAIT    The trait name   Added in PHP 5 4 0  As of PHP 5 4 this constant returns the trait as it was declared  case-sensitive   The trait name includes the namespace it was declared in  e g  Foo Bar      METHOD    The class method name   Added in PHP 5 0 0  The method name is returned as it was declared  case-sensitive      NAMESPACE    The name of the current namespace  case-sensitive   This constant is defined in compile-time  Added in PHP 5 3 0    Source

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Nullable return type declaration  PHP 7 adds support for return type declarations  Similarly to argument type declarations  return type declarations specify the type of value that will be returned from a function  The same types are available for return type declarations as are available for argument type declarations   Strict typing also has an effect on return type declarations  In the default weak mode  returned values will be coerced to the correct type if they are not already of that type  In strong mode  the returned value must be of the correct type  otherwise  a TypeError will be thrown   As of PHP 7 1 0  return values can be marked as nullable by prefixing the type name with a question mark      This signifies that the function returns either the specified type or NULL    lt  php function get item     string       if  isset   GET  item               return   GET  item          else           return null            gt    Source

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NullSafe Operator  quot  - gt  quot   possibly  since php8 In PHP8 it s been accepted this new operator   you can find the documentation here   - gt  it s the NullSafe Operator  it returns null in case you try to invoke functions or get values from null    Examples   lt  php  obj   null   obj    obj - gt attr    return null  obj    - gt funct       return null  obj    objDrive- gt attr     Error  Trying to get property  attr  of non-object   gt

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Null Coalesce operator       Added in PHP 7   Not the catchiest name for an operator  but PHP 7 brings in the rather handy null coalesce so I thought I d share an example   In PHP 5  we already have a ternary operator  which tests a value  and then returns the second element if that returns true and the third if it doesn t   echo  count    count   10     outputs 10   There is also a shorthand for that which allows you to skip the second element if it s the same as the first one  echo  count    10     also outputs 10  In PHP 7 we additionally get the    operator which rather than indicating extreme confusion which is how I would usually use two question marks together instead allows us to chain together a string of values  Reading from left to right  the first value which exists and is not null is the value that will be returned       a is not set  b   16   echo  a    2     outputs 2 echo  a     b    7     outputs 16   This construct is useful for giving priority to one or more values coming perhaps from user input or existing configuration  and safely falling back on a given default if that configuration is missing  It s kind of a small feature but it s one that I know I ll be using as soon as my applications upgrade to PHP 7

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QUESTION  What does   gt  mean   ANSWER    gt  Is the symbol we humans decided to use to separate  quot Key quot    gt   quot Value quot  pairs in Associative Arrays  ELABORATING  To understand this  we have to know what Associative Arrays are  The first thing that comes up when a conventional programmer thinks of an array  in PHP  would be something similar to   myArray1   array 2016   quot hello quot   33    option 1   myArray2    2016   quot hello quot   33    option 2   myArray3        option 3  myArray3     2016    myArray3      quot hello quot     myArray3     33   Where as  if we wanted to call the array in some later part of the code  we could do  echo  myArray1 1     output  hello echo  myArray2 1     output  hello echo  myArray3 1     output  hello  So far so good  However  as humans  we might find it hard to remember that index  0  of the array is the value of the year 2016  index  1  of the array is a greetings  and index  2  of the array is a simple integer value  The alternative we would then have is to use what is called an Associative Array  An Associative array has a few differences from a Sequential Array  which is what the previous cases were since they increment the index used in a predetermined sequence  by incrementing by 1 for each following value   Differences  between a sequential and associative array    Durring the declaration of an Associative Array  you don t only include the value of what you want to put in the array  but you also put the index value  called the key  which you want to use when calling the array in later parts of the code  The following syntax is used during it s declaration   quot key quot    gt   quot value quot    When using the Associative Array  the key value would then be placed inside the index of the array to retrieve the desired value    For instance   myArray1   array        quot Year quot    gt  2016        quot Greetings quot    gt   quot hello quot         quot Integer value quot    gt  33    option 1   myArray2           quot Year quot    gt   2016        quot Greetings quot    gt   quot hello quot         quot Integer value quot    gt  33    option 2   myArray3        option 3  myArray3  quot Year quot     2016    myArray3  quot Greetings quot      quot hello quot     myArray3  quot Integer value quot     33   And now  to receive the same output as before  the key value would be used in the arrays index  echo  myArray1  quot Greetings quot      output  hello echo  myArray2  quot Greetings quot      output  hello echo  myArray3  quot Greetings quot      output  hello  FINAL POINT  So from the above example  it is pretty easy to see that the   gt  symbol is used to express the relationship of an Associative Array between each of the key and value pairs in an array DURING the initiation of the values within the array

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lt   gt  Spaceship Operator  Added in PHP 7  The spaceship operator  lt   gt  is the latest comparison operator added in PHP 7  It is a non-associative binary operator with the same precedence as equality operators                     This operator allows for simpler three-way comparison between left-hand and right-hand operands   The operator results in an integer expression of    0 when both operands are equal Less than 0 when the left-hand operand is less than the right-hand operand Greater than 0 when the left-hand operand is greater than the right-hand operand   e g   1  lt   gt  1     0 1  lt   gt  2     -1 2  lt   gt  1     1   A good practical application of using this operator would be in comparison type callbacks that are expected to return a zero  negative  or positive integer based on a three-way comparison between two values  The comparison function passed to usort is one such example   Before PHP 7 you would write      arr    4 2 1 3    usort  arr  function   a   b        if   a  lt   b            return -1        elseif   a  gt   b            return 1        else           return 0              Since PHP 7 you can write      arr    4 2 1 3    usort  arr  function   a   b        return  a  lt   gt   b

[php] Reference — What does this symbol mean in PHP?

An overview of operators in PHP:

Logical Operators:

Comparison operators:

Arithmetic Operators:

Incrementing/Decrementing Operators:

Bitwise Operators:

String Operators:

Array Operators:

Assignment Operators:

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