php中For、While、Foreach的对比说明

for (initialization; condition; increment)
{
    code to be executed;
}

<?php
for($i=1; $i<=100000; $i++)
{    
   echo "The number is " . $i . "<br>";
}
?>

while (condition)
{
    code to be executed;
}

<?php
// If you had an array with fruit names and prices in you could use foreach
$fruit = array( 
    "orange" =--> "5.00", 
    "apple" => "2.50", 
    "banana" => "3.99" 
); 

foreach ($fruit as $key => $value) 
{ 
 "$key is $value dollars";
} 
?>

<?php    
// While Loop    
$a=0;    
     while($a < 1000)
    {
        $a++;
    }
?>

<?php    
  // For Loop    
    for($a = 0; $a < 1000;)
    {
     $a++;
    }
?>

<?php    
  $test = array(1 => "cat", "dog" => 0, "red" => "green", 5 => 4, 3, "me");    
  $keys = array_keys($test);    
  $size = sizeOf($keys);    
  for($a = 0; $a < $size; $a++)
 {        
    $t = $test[$keys[$a]];
  }
?>

<?php    
  $test = array(1 => "cat", "dog" => 0, "red" => "green", 5 => 4, 3, "me");    
  foreach($test as $t)
  {
    
 }
?>