Common functions in PHP

This article mainly introduces PHP commonly used functions, interested in the friend's reference, I hope to be helpful to everyone.

Array_intersect ()

Compares the key values of two arrays and returns the intersection:

<?php$a1=array ("A" = "red", "b" = "green", "c" = "Blue", "d" = "yellow"), $a 2=array ("e" = "red", "f" = > "Green", "g" = "blue"), $result =array_intersect ($a 1, $a 2);p Rint_r ($result);? >result:array ([A] = red [b] = green [c] = blue)

Array_keys () function

Returns a new array that contains all the key names in the array.

<?php$a=array ("Volvo" = "XC90", "BMW" and "X5", "Toyota" and "Highlander");p Rint_r (Array_keys ($a)); >result:array ([0] = Volvo [1] = BMW [2] = Toyota)

Array_key_exists () function

Checks whether the specified key name exists in an array, returns true if the key name exists, or False if the key name does not exist.

<?php    $a =array ("Volvo" = "XC90", "BMW" = "X5");        if (array_key_exists ("Volvo", $a))      {      echo "key exists!) ";      }    else      {      echo ' key does not exist! ";      }? >result: Key exists!

Array_merge () function

Combine two arrays into an array:

<?php$a1=array ("Red", "green"), $a 2=array ("Blue", "yellow");p Rint_r (Array_merge ($a 1, $a 2));? >result:array ([0] = + red [1] = green [2] = = Blue [3] = yellow)

Array_reverse ()

Returns an array in the reverse order of elements:

<?php$a=array ("A" = "Volvo", "B" and "BMW", "c" = "Toyota");p Rint_r (Array_reverse ($a));? >result:array ([c] = Toyota [b] = BMW [a] = Volvo)

Array_unshift () function

Used to insert a new element into an array. The value of the new array is inserted at the beginning of the array.

<?php$a=array ("A" = "red", "B" and "green"); Array_unshift ($a, "blue");p rint_r ($a); >result:array ([0] = blue [A] = red [b] = green)

Array_values

Returns an array that contains all the key values in the given array, but does not retain the key name.

<?php$a=array ("Name" = "Bill", "age" = "country" and "USA");p Rint_r (array_values ($a));? >result:array ([0] = Bill [1] [2] = USA)

Hash_equals

String comparisons to prevent timing attacks
Compares two strings, regardless of whether they are equal, the time consumption of this function is constant.
This function can be used in a string comparison scenario where you need to prevent timing attacks, for example, a scenario where you can compare a crypt () password hash value.

BOOL Hash_equals (String $known _string, string $user _string)

Parameters:
Known_string
string of known length, to participate in the comparison
User_string
User-supplied string

return value:
Returns TRUE when two strings are equal, otherwise FALSE.

<?php$expected  = crypt (' 12345 ', ' $2a$07$usesomesillystringforsalt$ '); $correct   = Crypt (' 12345 ', ' $2a$07$ usesomesillystringforsalt$ '); $incorrect = Crypt (' Apple ',  ' $2a$07$usesomesillystringforsalt$ '); Var_dump (Hash_ Equals ($expected, $correct)); Var_dump (Hash_equals ($expected, $incorrect));? >result:bool (TRUE) bool (false)

In_array () function

Searches the array for the presence of the specified value.

<?php$people = Array ("Bill", "Steve", "Mark", "David"), if (In_array ("Mark", $people))  {  echo "match found";  } else  {  echo "match not Found";  }? >result: Match found

sprintf () function

Replace the percent sign (%) with a variable that is passed as a parameter:

<?php    $number = 2;    $STR = "Shanghai";        $txt = sprintf ("There is%u million cars in%s.", $number, $str);        Echo $txt;? >    Result:there is 2 million cars in Shanghai.

Str_ireplace ()

Replace some characters in a string (case insensitive) str_ireplace (Find,replace,string,count)

<?phpecho Str_ireplace ("World", "Shanghai", "Hello world!");? >result:hello shanghai!

Strpos

Finds the position of the first occurrence of a string in another string.

<?phpecho Strpos ("You love php, I love php too!", "PHP"); >result:9

Str_replace ()

Replace some characters in a string with other characters (case sensitive)

<?phpecho Str_replace ("World", "Shanghai", "Hello world!");? >result:hello shanghai!

str_ireplace ()
Replace some characters in a string (case insensitive)
Str_ireplace (Find,replace,string,count)

<?phpecho Str_ireplace ("World", "Shanghai", "Hello world!");? >result:hello shanghai!

Substr

Returns a portion of a string.

<?phpecho substr ("Hello World", 6);? >result:world

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