关于php递归函数的问题

[qq599006169]

<?php
function draw($total,$line=1,$result="a1"){
    echo "<script>alert('$total,$line')</script>";
	if($line>$total){
        return;
    }
    else{
        $line++;
        //echo $result;
        echo "<script>alert('draw1($total,$line,$result)')</script>";
        draw($total,$line,$result);
        echo "<script>alert('draw2($total,$line,$result)')</script>";
	}
	echo $result;
}
draw(3);
?>

语句中执行函数draw(3)，当运行到if($line>$total){return;}echo出来三条信息draw2(3,4,a1)-->draw2(3,3,a1)-->draw2(3,2,a1)然后结束，请问是什么 原因使$line在return发生后，依次减1呢？

[xuzuning]

没有原因，因为他并没有变

function draw($total,$line=1,$result="a1"){
    echo "<script>alert('$total,$line')</script>";
    if($line>$total){
        return;
    }
    else{
        $line++;
        //echo $result;
        echo "<script>alert('draw1($total,$line,$result)')</script>";
echo "递归前 line = $line\n";
        draw($total,$line,$result);
echo "递归后 line = $line\n";
        echo "<script>alert('draw2($total,$line,$result)')</script>";
    }
    echo $result;
}
draw(3);

[qq599006169]

谢谢，我想我递归的原理还没弄明白，再去找下资料吧