将数组键转换为格式化的类名

Question

I need to take this array and convert only the keys into one string. Looking for an efficient way to do this.

1. Each element having a period added before the name ( .first_post )
2. Concatenated with another string and space before each class name ( .navigation .first_post )
3. A comma after the name ( .navigation .first_post, )
4. Replace the "_" to "-" ( .navigation .first-post, )

Items

array (
  'first_post' => 'First Post' 
  'first_page' => 'First Page' 
  'prev_page' => 'Previous Page'
  'next_page' => 'Next Page'
  'last_page' => 'Last Page'
  'last_post' => 'Last Post'
);

This is what I am hoping for

.navigation .first-post, .navigation .first-page, .navigation .prev-post,
.navigation .next-page, .navigation .last-page, .navigation .last-post

Answer 1

array_map gives you an elegant way of applying a transformation to each of an array's elements. After doing that, all you need to do is implode the result to concatenate all the values:

$arr = array (
  'first_post' => 'First Post',
  'first_page' => 'First Page',
  'prev_page' => 'Previous Page',
  'next_page' => 'Next Page',
  'last_page' => 'Last Page',
  'last_post' => 'Last Post'
);

function transform($x) {
    return '.navigation .' . str_replace('_', '-', $x);
};

$result = implode(', ', array_map('transform', array_keys($arr)));

Answer 2

Try to replace/add key with new values

foreach($arr as $k=>$v){
    $k = '.navigation .'.str_replace('_', '-', $k);
    $newarr[$k] = $v;
}
print_r($newarr);

if you want keys as comma separated string

$str = implode(", ", array_keys($newarr))