array_shift
—
Shift an element off the beginning of array
Description
array_shift(array&$array):mixed
array_shift()
shifts the first value of the
array
off and returns it, shortening the
array
by one element and moving everything down. All numerical array keys will be modified to start counting from zero while literal keys won't be affected.
Note
:
This function will
reset()
the
array
pointer of the input array after use.
Parameters
array
The input array.
Return Values
Returns the shifted value, or
null
if
array
is empty or is not an array.
array_slice()
returns the sequence of elements from the array
array
as specified by the
offset
and
length
parameters.
Parameters
array
The input array.
offset
If
offset
is non-negative, the sequence will start at that offset in the
array
.
If
offset
is negative, the sequence will start that far from the end of the
array
.
Note
:
The
offset
parameter denotes the position in the array, not the key.
length
If
length
is given and is positive, then the sequence will have up to that many elements in it.
If the array is shorter than the
length
, then only the available array elements will be present.
If
length
is given and is negative then the sequence will stop that many elements from the end of the array.
If it is omitted, then the sequence will have everything from
offset
up until the end of the
array
.
preserve_keys
Note
:
array_slice()
will reorder and reset the integer array indices by default. This behaviour can be changed by setting
preserve_keys
to
true
. String keys are always preserved, regardless of this parameter.
Return Values
Returns the slice. If the offset is larger than the size of the array, an empty array is returned.
Examples
Example #1
array_slice()
examples
<?php$input=array("a","b","c","d","e");$output=array_slice($input,2);// returns "c", "d", and "e"$output=array_slice($input,-2,1);// returns "d"$output=array_slice($input,0,3);// returns "a", "b", and "c"// note the differences in the array keysprint_r(array_slice($input,2,-1));print_r(array_slice($input,2,-1,true));?>
The above example will output:
Array
(
[0] => c
[1] => d
)
Array
(
[2] => c
[3] => d
)
Removes the elements designated by
offset
and
length
from the
array
array, and replaces them with the elements of the
replacement
array, if supplied.
Note
:
Numerical keys in
array
are not preserved.
Note
:
If
replacement
is not an array, it will be typecast to one (i.e.
(array) $replacement
). This may result in unexpected behavior when using an object or
null
replacement
.
Parameters
array
The input array.
offset
If
offset
is positive then the start of the removed portion is at that offset from the beginning of the
array
array.
If
offset
is negative then the start of the removed portion is at that offset from the end of the
array
array.
length
If
length
is omitted, removes everything from
offset
to the end of the array.
If
length
is specified and is positive, then that many elements will be removed.
If
length
is specified and is negative, then the end of the removed portion will be that many elements from the end of the array.
If
length
is specified and is zero, no elements will be removed.
Tip
To remove everything from
offset
to the end of the array when
replacement
is also specified, use
count($input)
for
length
.
replacement
If
replacement
array is specified, then the removed elements are replaced with elements from this array.
If
offset
and
length
are such that nothing is removed, then the elements from the
replacement
array are inserted in the place specified by the
offset
.
Note
:
Keys in the
replacement
array are not preserved.
If
replacement
is just one element it is not necessary to put
array()
or square brackets around it, unless the element is an array itself, an object or
null
.
Return Values
Returns an array consisting of the extracted elements.
Example #2 Equivalent statements to various
array_splice()
examples
The following statements are equivalent:
<?php// append two elements to $inputarray_push($input,$x,$y);array_splice($input,count($input),0,array($x,$y));// remove the last element of $inputarray_pop($input);array_splice($input,-1);// remove the first element of $inputarray_shift($input);array_splice($input,0,1);// insert an element at the start of $inputarray_unshift($input,$x,$y);array_splice($input,0,0,array($x,$y));// replace the value in $input at index $x$input[$x]=$y;// for arrays where key equals offsetarray_splice($input,$x,1,$y);?>
Computes the difference of arrays by using a callback function for data comparison. This is unlike
array_diff()
which uses an internal function for comparing the data.
Parameters
array
The first array.
arrays
Arrays to compare against.
value_compare_func
The callback comparison function.
The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.
callback(mixed$a,mixed$b):int
Return Values
Returns an array containing all the values of
array
that are not present in any of the other arguments.
Examples
Example #1
array_udiff()
example using stdClass Objects
<?php// Arrays to compare$array1=array(newstdclass,newstdclass,newstdclass,newstdclass,);$array2=array(newstdclass,newstdclass,);// Set some properties for each object$array1[0]->width=11;$array1[0]->height=3;$array1[1]->width=7;$array1[1]->height=1;$array1[2]->width=2;$array1[2]->height=9;$array1[3]->width=5;$array1[3]->height=7;$array2[0]->width=7;$array2[0]->height=5;$array2[1]->width=9;$array2[1]->height=2;functioncompare_by_area($a,$b){$areaA=$a->width*$a->height;$areaB=$b->width*$b->height;if($areaA<$areaB){return-1;}elseif($areaA>$areaB){return1;}else{return0;}}print_r(array_udiff($array1,$array2,'compare_by_area'));?>
Example #2
array_udiff()
example using DateTime Objects
<?phpclassMyCalendar{public$free=array();public$booked=array();publicfunction__construct($week='now'){$start=newDateTime($week);$start->modify('Monday this week midnight');$end=clone$start;$end->modify('Friday this week midnight');$interval=newDateInterval('P1D');foreach(newDatePeriod($start,$interval,$end)as$freeTime){$this->free[]=$freeTime;}}publicfunctionbookAppointment(DateTime$date,$note){$this->booked[]=array('date'=>$date->modify('midnight'),'note'=>$note);}publicfunctioncheckAvailability(){returnarray_udiff($this->free,$this->booked,array($this,'customCompare'));}publicfunctioncustomCompare($free,$booked){if(is_array($free))$a=$free['date'];else$a=$free;if(is_array($booked))$b=$booked['date'];else$b=$booked;if($a==$b){return0;}elseif($a>$b){return1;}else{return-1;}}}// Create a calendar for weekly appointments$myCalendar=newMyCalendar;// Book some appointments for this week$myCalendar->bookAppointment(newDateTime('Monday this week'),"Cleaning GoogleGuy's apartment.");$myCalendar->bookAppointment(newDateTime('Wednesday this week'),"Going on a snowboarding trip.");$myCalendar->bookAppointment(newDateTime('Friday this week'),"Fixing buggy code.");// Check availability of days by comparing $booked dates against $free datesecho"I'm available on the following days this week...\n\n";foreach($myCalendar->checkAvailability()as$free){echo$free->format('l'),"\n";}echo"\n\n";echo"I'm busy on the following days this week...\n\n";foreach($myCalendar->bookedas$booked){echo$booked['date']->format('l'),": ",$booked['note'],"\n";}?>
The above example will output:
I'm available on the following days this week...
Tuesday
Thursday
I'm busy on the following days this week...
Monday: Cleaning GoogleGuy's apartment.
Wednesday: Going on a snowboarding trip.
Friday: Fixing buggy code.
Notes
Note
:
Please note that this function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using
array_udiff($array1[0], $array2[0], "data_compare_func");
.
See Also
array_diff() - Computes the difference of arrays
array_diff_assoc() - Computes the difference of arrays with additional index check
array_diff_uassoc() - Computes the difference of arrays with additional index check which is performed by a user supplied callback function
array_udiff_assoc() - Computes the difference of arrays with additional index check, compares data by a callback function
array_udiff_uassoc() - Computes the difference of arrays with additional index check, compares data and indexes by a callback function
array_intersect() - Computes the intersection of arrays
array_intersect_assoc() - Computes the intersection of arrays with additional index check
array_uintersect() - Computes the intersection of arrays, compares data by a callback function
array_uintersect_assoc() - Computes the intersection of arrays with additional index check, compares data by a callback function
array_uintersect_uassoc() - Computes the intersection of arrays with additional index check, compares data and indexes by separate callback functions
Computes the difference of arrays with additional index check, compares data by a callback function.
Note
:
Please note that this function only checks one dimension of a n-dimensional array. Of course you can check deeper dimensions by using, for example,
array_udiff_assoc($array1[0], $array2[0], "some_comparison_func");
.
Parameters
array
The first array.
arrays
Arrays to compare against.
value_compare_func
The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.
callback(mixed$a,mixed$b):int
Return Values
array_udiff_assoc()
returns an
array
containing all the values from
array
that are not present in any of the other arguments. Note that the keys are used in the comparison unlike
array_diff()
and
array_udiff()
. The comparison of arrays' data is performed by using an user-supplied callback. In this aspect the behaviour is opposite to the behaviour of
array_diff_assoc()
which uses internal function for comparison.