function alert($title){
  echo "<script type='text/javascript'>alert('$title');</script>";
}

function href($url){
  echo "<script type='text/javascript'>window.location.href='$url'</script>";
}

function println($string){
    echo $string."<br>";
}

function printline(){
    echo "<hr color='red' width='20%' align='left'>";
}

$str = "1,2,3,4,5,6,"; 
$newstr = substr($str,0,strlen($str)-1); 
echo $newstr; 
//echo 1,2,3,4,5,6

substr($str, 0, -1)

rtrim($str, ",")

substr_replace($string ,"",-1);

<?php
$str = '这样一来我的字符串就不会有乱码^_^';

echo "mb_substr:" . mb_substr($str, 0, 7, 'utf-8');
//结果：这样一来我的字
echo "<br>";

echo "mb_strcut:" . mb_strcut($str, 0, 6, 'utf-8');
//结果：这样
?>