Detailed explanation of how to obtain a specified number of random strings in php

function getARandLetter($number = 1) {
 if ($number == 0)
  return FALSE; //去除0
 $number = $number < 0 ? - $number : $number; //如果小于零取正值
 $letterArr = array (&#39;A&#39;, &#39;B&#39;, &#39;C&#39;, &#39;D&#39;, &#39;E&#39;, &#39;F&#39;, &#39;G&#39;, &#39;H&#39;, &#39;I&#39;, &#39;J&#39;, &#39;K&#39;, &#39;L&#39;, &#39;M&#39;, &#39;N&#39;, &#39;O&#39;, &#39;P&#39;, &#39;Q&#39;, &#39;R&#39;, &#39;S&#39;, &#39;T&#39;, &#39;U&#39;, &#39;V&#39;, &#39;W&#39;, &#39;X&#39;, &#39;Y&#39;, &#39;Z&#39;, &#39;a&#39;, &#39;b&#39;, &#39;c&#39;, &#39;d&#39;, &#39;e&#39;, &#39;f&#39;, &#39;g&#39;, &#39;h&#39;, &#39;i&#39;, &#39;j&#39;, &#39;k&#39;, &#39;l&#39;, &#39;m&#39;, &#39;n&#39;, &#39;o&#39;, &#39;p&#39;, &#39;q&#39;, &#39;r&#39;, &#39;s&#39;, &#39;t&#39;, &#39;u&#39;, &#39;v&#39;, &#39;w&#39;, &#39;x&#39;, &#39;y&#39;, &#39;z&#39; );
 $returnStr =&#39;&#39;;
 for($i= 0; $i < $number; $i ++) {
  $returnStr .= $letterArr [rand ( 0, 51 )];
 }
 return $returnStr;
}
echo getARandLetter(8);