I need to have an array_search search my array strictly making sure that the item is identical (meaning the whole thing is the same thing as the input value). I know about the third variable in a array_search() function in PHP - the Strict one, but I don't want it to check if its the same instance, as it is not. How would I do this?
Here is the code I'm currently using:
array_search(some, array(someItem,anothervariable, yetanothervariable, some));
//output - 0 (the first item) which contains some but isn't exactly some.
Requested output:
Instead of outputting the first item that contains some, someItem, it would output the key for the last item, 3, that is the exact search value.
Array search with strict is equivalent to the === operator.
Array search without strict is equivalent to the == operator.
If you need some sort of special comparison that isn't covered by either of them (comparing elements of objects for example) then you need to write a loop.
Are you open to using a foreach loop instead of array_search?
If so try this:
$haystack = array('something', 'someone', 'somewhere', 'some');
$needle = 'some';
foreach($haystack as $key=>$straw){
if($straw === $needle){
$straws[$key] = $straw;
}
}
print_r($straws);
it will print
Array ( [3] => some )
Or you could use array_keys() with the search value specified.
Then, using the same $haystack and $needle above:
$result = array_keys($haystack,$needle,TRUE);
print_r($result);
This returns:
Array ( [0] => 3 )
The first argument is the array to return keys from, The second arg is the search value, if you include this arg, then only keys from array elements that match the search value are returned. Including the third boolean arg tells the function to use match type as well (===).
Not really sure what you are asking but in PHP strict comparison is achieved with the
triple equal sign (===). This means that both the value and the type must be the same.
So if you compare a string "1" and an integer 1 with === it will fail.
If strict is false then comparing string "1" with integer 1 would succeed.
This is the meaning of strict in the array_search case.
I implemented array_search below so you can see what it is doing.
function my_array_search($input, $search_array, $strict=false) {
if(is_array($search_array)) {
foreach($search_array as $key => $val) {
if($strict === true) {
if($val === $input) {
return $key;
}
} else {
if($val == $input) {
return $key;
}
}
}
}
}
Related
Why does the following code work:
$test = array(0=>'test1','field0'=>'test2',1=>'test3','field1'=>'test4');
echo array_search('test4',$test);
But the following doesn't:
$test = array(0=>0,'field0'=>'test2',1=>'test3','field1'=>'test4');
echo array_search('test4',$test);
If you had a mixed array from say mysql_fetch_array($result,MYSQL_BOTH) and took the keys which you needed to search you wouldn't be able too - it would never progress further than 0.
Try to do array_search('test4',$test, TRUE);. The 3rd parameter tells it to use === instead of == when comparing.
Since your array holds both strings and numbers, when it compares to the 0 (the 1st element), it converts 'test4' to a number (it stops at the 1st non-numeric character) and it happens to match.
What I mean is: 'test4' == 0 => 0 == 0 => true.
When you pass TRUE as the 3rd parameter, it uses ===, and 'test4' === 0 is automatically false since the types don't match, there is no conversion.
The solution = force the 0 value to be a string:
$test = array(0=>0,'field0'=>'test2',1=>'test3','field1'=>'test4');
foreach ($test as $k=>$v){ $test[$k] = (string) $v; }
echo array_search('test4',$test);
You can't search a number for a string and expect a good result.
My guess is it sees the value as a number, so it converts your string to a number (which it can't) so that string gets converted to a 0. So the value of 0 equals the search string, which also equals 0, and there's your result.
If the value is 1, it won't match as the search string gets converted to a 0 (as you can't convert a string to a number) so it wouldn't match in the following.
$test = array(0=>1,'field0'=>'test2',1=>'test3','field1'=>'test4');
You'll only get your exact case scenario when that value in the array is 0.
I am trying to search an array and see if a value is contained in it. If the value is in the array then the index of the value in the array will be passed onto be removed from the array.
The problem is array_search returns FALSE if the value is not found, but since false is a boolean it is also treated as 0. When this is passed to the unset to remove the value from the array the value at index 0 will be removed if array_search returned false.
I am fairly sure it will need to be put into an if statement but how will I handle the response if both an integer and a boolean can both be returned?
Current Code:
$pos = array_search($value, $array);
unset($array[$pos]);
PHP Doc says..
This function may return Boolean FALSE, but may also return a
non-Boolean value which evaluates to FALSE. Please read the section on
Booleans for more information. Use the === operator for testing the
return value of this function.
So you need to do like this
<?php
$arr = [1,2,3];
$pos = array_search(4, $arr);
if($pos!==false)
{
unset($arr[$pos]);
}
print_r($arr);
OUTPUT
Array
(
[0] => 1
[1] => 2
[2] => 3
)
As you can see the first index is retained.
try this
if($pos !== false)
{
// do your work to unset
}
note !== in above code
$x !== $y is True if $x is not equal to $y, or they are not of the same type
You can try this script, hope this will help you...
if(in_array($value, $array)){
$pos = array_search($value, $array);
unset($array[$pos]);
}
I need to check if all values in an array equal the same thing.
For example:
$allValues = array(
'true',
'true',
'true',
);
If every value in the array equals 'true' then I want to echo 'all true'. If any value in the array equals 'false' then I want to echo 'some false'
Any idea on how I can do this?
All values equal the test value:
// note, "count(array_flip($allvalues))" is a tricky but very fast way to count the unique values.
// "end($allvalues)" is a way to get an arbitrary value from an array without needing to know a valid array key. For example, assuming $allvalues[0] exists may not be true.
if (count(array_flip($allvalues)) === 1 && end($allvalues) === 'true') {
}
or just test for the existence of the thing you don't want:
if (in_array('false', $allvalues, true)) {
}
Prefer the latter method if you're sure that there's only 2 possible values that could be in the array, as it's much more efficient. But if in doubt, a slow program is better than an incorrect program, so use the first method.
If you can't use the second method, your array is very large, and the contents of the array is likely to have more than 1 value (especially if the 2nd value is likely to occur near the beginning of the array), it may be much faster to do the following:
/**
* Checks if an array contains at most 1 distinct value.
* Optionally, restrict what the 1 distinct value is permitted to be via
* a user supplied testValue.
*
* #param array $arr - Array to check
* #param null $testValue - Optional value to restrict which distinct value the array is permitted to contain.
* #return bool - false if the array contains more than 1 distinct value, or contains a value other than your supplied testValue.
* #assert isHomogenous([]) === true
* #assert isHomogenous([], 2) === true
* #assert isHomogenous([2]) === true
* #assert isHomogenous([2, 3]) === false
* #assert isHomogenous([2, 2]) === true
* #assert isHomogenous([2, 2], 2) === true
* #assert isHomogenous([2, 2], 3) === false
* #assert isHomogenous([2, 3], 3) === false
* #assert isHomogenous([null, null], null) === true
*/
function isHomogenous(array $arr, $testValue = null) {
// If they did not pass the 2nd func argument, then we will use an arbitrary value in the $arr (that happens to be the first value).
// By using func_num_args() to test for this, we can properly support testing for an array filled with nulls, if desired.
// ie isHomogenous([null, null], null) === true
$testValue = func_num_args() > 1 ? $testValue : reset($arr);
foreach ($arr as $val) {
if ($testValue !== $val) {
return false;
}
}
return true;
}
Note: Some answers interpret the original question as (1) how to check if all values are the same, while others interpreted it as (2) how to check if all values are the same and make sure that value equals the test value. The solution you choose should be mindful of that detail.
My first 2 solutions answered #2. My isHomogenous() function answers #1, or #2 if you pass it the 2nd arg.
Why not just compare count after calling array_unique()?
To check if all elements in an array are the same, should be as simple as:
$allValuesAreTheSame = (count(array_unique($allValues, SORT_REGULAR)) === 1);
This should work regardless of the type of values in the array.
Update: Added the SORT_REGULAR flag to avoid implicit type-casting as pointed out by Yann Chabot
Also, you can condense goat's answer in the event it's not a binary:
if (count(array_unique($allvalues)) === 1 && end($allvalues) === 'true') {
// ...
}
to
if (array_unique($allvalues) === array('foobar')) {
// all values in array are "foobar"
}
If your array contains actual booleans (or ints) instead of strings, you could use array_sum:
$allvalues = array(TRUE, TRUE, TRUE);
if(array_sum($allvalues) == count($allvalues)) {
echo 'all true';
} else {
echo 'some false';
}
http://codepad.org/FIgomd9X
This works because TRUE will be evaluated as 1, and FALSE as 0.
You can compare min and max... not the fastest way ;p
$homogenous = ( min($array) === max($array) );
$alltrue = 1;
foreach($array as $item) {
if($item!='true') { $alltrue = 0; }
}
if($alltrue) { echo("all true."); }
else { echo("some false."); }
Technically this doesn't test for "some false," it tests for "not all true." But it sounds like you're pretty sure that the only values you'll get are 'true' and 'false'.
Another option:
function same($arr) {
return $arr === array_filter($arr, function ($element) use ($arr) {
return ($element === $arr[0]);
});
}
Usage:
same(array(true, true, true)); // => true
Answering my method for people searching in 2023.
$arr = [5,5,5,5,5];
$flag = 0;
$firstElement = $arr[0];
foreach($arr as $val){
// CHECK IF THE FIRST ELEMENT DIFFERS FROM ANY OTHER ELEMENT IN THE ARRAY
if($firstElement != $val){
// FIRST MISMATCH FOUND. UPDATE FLAG VALUE AND BREAK OUT OF THE LOOP.
$flag = 1;
break;
}
}
if($flag == 0){
// ALL THE ELEMENTS ARE SAME... DO SOMETHING
}else{
// ALL THE ELEMENTS ARE NOT SAME... DO SOMETHING
}
In an array where all elements are same, it should always be true that all the elements MUST match with the first element of the array. Keeping this logic in mind, we can get the first element of the array and iterate through each element in the array to check for that first element in the loop which does not match with the first element in the array. If found, we will change the flag value and break out of the loop immediately. Else, the loop will continue till it reaches the end. Later, outside the loop, we can use this flag value to determine if all the elements in the array are same or not.
This solution is good for arrays with definite limit of elements (small array). However, I am not sure how good this solution would be for arrays with very large number of elements present considering that we are looping through each and every element to check for the first break even point. Please use this solution at your own convenience and judgement.
$x = 0;
foreach ($allvalues as $a) {
if ($a != $checkvalue) {
$x = 1;
}
}
//then check against $x
if ($x != 0) {
//not all values are the same
}
Here is some code I have: (p just echos plus adds a newline)
foreach ($vanSteps as $k => $reqInfo)
{
p($k);
if ('van' == $k) { p('The key is the van, continue'); continue; }//continue if we reached the part of the array where van is key
//do stuff
}
and I'm getting this output:
0
The key is the van, continue
1
2
3
van
The key is the van, continue
Why does the if statement return true when the key is 0? This foreach loop handles logic that applies when the key == 0 (and any other key except if the key is 'van') and this messes up the logic because it's return true when key is 0.
Any help?
Thank you.
Use === for this comparison. When PHP compares string and integer it first casts string to integer value and then does comparison.
See Comparison Operators in manual.
In PHP 'van' == 0 is true. This is because when using == to compare a string and a number, the string is converted to a number (as described in the second link below); this makes the comparison internally become 0 == 0 which is of course true.
The suggested alternative for your needs, would be to use a strict equality comparison using ===.
See Comparison Operators and String conversion to numbers
In PHP, when you compare 2 types, it has to convert them to the same type. In your case, you compare string with int.
Internally this gets converted to
if((int)'van'==0)....
and then
if((int)'van'==1)....
(int)'any possible string' will be 0:) So you either have to manually convert the both values to the same type, or use === as a comparison operator, instead of the loose =.
An exception from this rule(as pointed out in the comments) would be if the string start with a number, or can be interpreted as a number in any way(1, 0002, -1 etc). In this case, the string would be interpreted as a number, diregarding the end of the non-numeric end-of-string
Take a look at http://php.net/manual/en/types.comparisons.php for more details.
This works fine:
$array = array(0=>"a",1=>"b","van"=>"booya!");
function p($v){ echo "{$v}<br />"; }
foreach ($array as $k => $reqInfo)
{
p($k);
if ('van' === $k) { p('The key is the van, continue'); continue; }//continue if we reached the part of the array where van is key
//do stuff
}
Output:
0
1
van
The key is the van, continue
Note the ===.
Read the Comparison with Various Types table
When one of the operand is number, the other operand is converted to number too. Since 'van' is non-numeric sting, it's converted to 0. You should use === operator in the case, which also checks the variable type
That's becuase 'van' == 0 (true).
Instead, you should use 'van' === 0 (false).
In short, use === instead of ==.
Its interpreting the 'van' as a boolean value (false) which 0 is equal to.
To check for exact matches in type and value in PHP you must use === instead of ==
In PHP, will these always return the same values?
//example 1
$array = array();
if ($array) {
echo 'the array has items';
}
// example 2
$array = array();
if (count($array)) {
echo 'the array has items';
}
Thank you!
From http://www.php.net/manual/en/language.types.boolean.php, it says that an empty array is considered FALSE.
(Quoted):
When converting to boolean, the following values are considered FALSE:
the boolean FALSE itself
the integer 0 (zero)
the float 0.0 (zero)
the empty string, and the string "0"
an array with zero elements
an object with zero member variables (PHP 4 only)
the special type NULL (including unset variables)
SimpleXML objects created from empty tags
Since
a count() of > 0 IS NOT FALSE
a filled array IS NOT FALSE
then both cases illustrated in the question will always work as expected.
Those will always return the same value, but I find
$array = array();
if (empty($array)) {
echo 'the array is empty';
}
to be a lot more readable.
Note that the second example (using count()) is significantly slower, by at least 50% on my system (over 10000 iterations). count() actually counts the elements of an array. I'm not positive, but I imagine casting an array to a boolean works much like empty(), and stops as soon as it finds at least one element.
Indeed they will. Converting an array to a bool will give you true if it is non-empty, and the count of an array is true with more than one element.
See also: http://ca2.php.net/manual/en/language.types.boolean.php#language.types.boolean.casting