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php – selecting an array key based on partial string

Posted by: admin April 23, 2020 Leave a comment

Questions:

I have an array and in that array I have an array key that looks like, show_me_160 this array key may change a little, so sometimes the page may load and the array key maybe show_me_120, I want to now is possible to just string match the array key up until the last _ so that I can check what the value is after the last underscore?

How to&Answers:

one solution i can think of:

foreach($myarray as $key=>$value){
  if("show_me_" == substr($key,0,8)){
    $number = substr($key,strrpos($key,'_'));
    // do whatever you need to with $number...
  }
}

Answer:

I ran into a similar problem recently. This is what I came up with:

$value = $my_array[current(preg_grep('/^show_me_/', array_keys($my_array)))];

Answer:

you would have to iterate over your array to check each key separately, since you don’t have the possibility to query the array directly (I’m assuming the array also holds totally unrelated keys, but you can skip the if part if that’s not the case):

foreach($array as $k => $v)
{
  if (strpos($k, 'show_me_') !== false)
  {
    $number = substr($k, strrpos($k, '_'));
  }
}

However, this sounds like a very strange way of storing data, and if I were you, I’d check if there’s not an other way (more efficient) of passing data around in your application 😉

Answer:

You can also use a preg_match based solution:

foreach($array as $str) {
        if(preg_match('/^show_me_(\d+)$/',$str,$m)) {
                echo "Array element ",$str," matched and number = ",$m[1],"\n";
        }
}

Answer:

to search for certain string in array keys you can use array_filter(); see docs

// the array you'll search in
$array = ["search_1"=>"value1","search_2"=>"value2","not_search"=>"value3"];
// filter the array and assign the returned array to variable
$foo = array_filter(
    // the array you wanna search in
    $array, 
    // callback function to search for certain sting
    function ($key){ 
        return(strpos($key,'search_') !== false);
    }, 
    // flag to let the array_filter(); know that you deal with array keys
    ARRAY_FILTER_USE_KEY
);
// print out the returned array
print_r($foo);

if you search in the array values you can use the flag 0 or leave the flag empty

$foo = array_filter(
    // the array you wanna search in
    $array, 
    // callback function to search for certain sting
    function ($value){ 
        return(strpos($value,'value') !== false);
    }, 
    // flag to let the array_filter(); know that you deal with array value
    0
);

or

$foo = array_filter(
    // the array you wanna search in
    $array, 
    // callback function to search for certain sting
    function ($value){ 
        return(strpos($value,'value') !== false);
    }
);

if you search in the array values and array keys you can use the flag ARRAY_FILTER_USE_BOTH

$foo = array_filter(
    // the array you wanna search in
    $array, 
    // callback function to search for certain sting
    function ($value, $key){ 
        return(strpos($key,'search_') !== false or strpos($value,'value') !== false);
    },
    ARRAY_FILTER_USE_BOTH
);

in case you’ll search for both you have to pass 2 arguments to the callback function

Answer:

 foreach($myarray as $key=>$value)
    if(count(explode('show_me_',$event_key)) > 1){
         //if array key contains show_me_
    }

More information (example):

if array key contain ‘show_me_’

$example = explode(‘show_me_’,’show_me_120′);

print_r($example)

Array ( [0] => [1] => 120 ) 

print_r(count($example))

2 

print_r($example[1])

 120 

Answer:

filter_array($array,function ($var){return(strpos($var,’searched_word’)!==FALSE);},);

return array ‘searched_key’ => ‘value assigned to the key’

Answer:

I recently had a similar challenge where I needed to scan a large multi-dimensional array for keys with a certain prefix so created a couple of functions for searching recursively for keys both case-sensitive and case-insensitively.

I’ve put these up on Github at the link below in the hope they’ll help someone else trying to do the same!

https://gist.github.com/aran112000/c77a8d8f4c41af6f5800b485caf94fa9