Merge arrays with strings and delete repetitive values in PHP - php

Question

From WP_Query I am dumping strings stored into separate arrays:
array(1) {
[0]=>
string(8) "Portugal"
}
array(1) {
[0]=>
string(5) "Spain"
}
array(1) {
[0]=>
string(5) "Italy"
}
array(1) {
[0]=>
string(6) "Monaco"
}
array(1) {
[0]=>
string(5) "Spain"
}
array(1) {
[0]=>
string(9) "Lithuania"
}
I am trying to merge those arrays into one array, delete repetitive strings like "Spain" and get the number of unique values.
I was trying to use array_merge():
$tester = array();
foreach($array_string as $value) {
array_merge($tester, $value);
}
$result = array_unique($tester);
print_r($result);
But without any decent results, error telling that <b>Warning</b>: array_merge(): Argument #2 is not an array Could someone tell where I am missing the point? Many thanks for all possible help, will be looking forward.

Answer 1

The code posted in the question is almost good. The intention is correct but you missed out a simple thing: you initialize $tester with an empty array and then never add something to it. In the end, it is still empty and array_unique() has nothing to do but return an empty array too.
The error is in the line:
array_merge($tester, $value);
array_merge() does not change the arrays passed to it as argument. It returns a new array that your code ignores (instead of saving it into $tester).
This is how your code should look like:
$tester = array();
foreach($array_string as $value) {
$tester = array_merge($tester, $value);
}
$result = array_unique($tester);
print_r($result);
Solution #2
You can use call_user_func_array() to invoke array_merge() and pass the values of $array_string as arguments. The returned array contains duplicates; passing it to array_unique() removes them:
$result = array_unique(call_user_func_array('array_merge', $array_string));
Solution #3
A simpler (and possibly faster) way to accomplish the same thing is to use array_column() to get the values into an array and then pass it to array_unique(), of course:
$result = array_unique(array_column($array_string, 0));
This solution works only with PHP 5.5 or newer (the array_column() function doesn't exist in older versions.)

Answer 2

To get the number of unique strings in the merged array you will have to set empty array before WP_Query
$tester = array();
Than inside while loop of WP_Query every string is put into separate array and pushed to $tester
foreach((array)$array_string as $key=>$value[0]) {
array_push($tester,$value);
}
Unique values in array $tester is found using array_unique() functions that should be placed after WP_Query while loop.
$unique_array_string = array_unique($tester, SORT_REGULAR);
$unique_string_number = sizeof($unique_array_string);

Answer 3

You will create an array and will take key of the array for cities names like spain..etc And it will give different cities name always...
$data= array();
$data1 = array("Portugal");
$data2 = array("Spain");
$data3 = array("Italy");
$data4 = array("Monaco");
$data5 = array("Spain");
$data6 = array("Lithuania");
$merge = array_merge($data1, $data2,$data3,$data4,$data5,$data6);
$data = array();
foreach($merge as $value) {
$data[$value] = $value;
}
echo '<pre>',print_r($data),'</pre>';