How does an array like this make its tree-like display?

Tree-like infinite classification

Array ([    1] = = Array        (            [id] = 1            [name] = + World            [PID] + 0            [2] = = Array                (                    [ ID] + 2                    [name] + China                    [PID] + 1                    [4] = = Array                        (                            [id] + 4                            [name]                            = + Hunan [PID] + 2                        )                )            [3] = = Array                (                    [id] + 3                    [name] = + US                    [pid] + 1                )        ))

Reply to discussion (solution)

itself is a tree-like, PID is not simple? Just a recursive line.

$a = Array (  1 = = Array (    ' id ' = = 1,    ' name ' = ' World ',    ' pid ' = = 0,    2 = = Array (      ' id ' =&G T 2,      ' name ' = ' China ',      ' pid ' = + 1,      4 = = Array (        ' id ' = = 4,        ' name ' = ' hu ') ', '        pid ' => ; 2,      ),    ),    3 = = Array (      ' id ' = + 3,      ' name ' = ' Us ',      ' pid ' = 1,  '),) ; tree ($a); function tree ($ar) {  if (! Is_array ($ar)) return;  Echo '
 
  
  

   
   
  ;  foreach ($ar as $item) {    echo "$item [id] $item [name]";    foreach ($item as $t) {      if (Is_array ($t)) {        tree (Array ($t))  }}} Echo '
 
  
  
;}

1 World 2 China 4 Hunan 3 USA

 
  
  

   
   
  1 World
  
   
   

     2 China 
    

      4 hunan 
    
 
   
  
   
   

     3 USA 
   
 
  
  

I'll give you an interesting play (I don't know what to do with it)

$a = Array (  1 = = Array (    //' id ' = + 1,    ' name ' = = ' world ',    //' pid ' = 0,    2 = = Array (      // ' id ' = 2,      ' name ' = ' China ', '/      ' pid ' = + 1,      4 = = Array (        //' id ' = + 4,        ' name ' = ' Hunan ') ,        //' pid ' = 2,      ),    3 = = Array (      //' id ' = + 3,      ' name ' = ' US ',      //' pid ' = > 1,),)  , $awesome = new Recursivetreeiterator (      new Recursivearrayiterator ($a),      null, NULL, Recursiveiteratoriterator::leaves_only  );  The echo $line of the foreach ($awesome as $line)      . Php_eol;  

  |-World | |-  China  |   \-Hunan    \-USA

Grey often thanks! Cry!! It's been a few days,,,

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