php在foreach内部追加，追加到变量的用途是什么。

如何将代码附加到变量

<?php
echo "<ul>\n";
    foreach($related as $r) {

        if ($r->Count > 0) {
            echo "<li>" . "<a>". $r->post_title ."</a>". "\n";
      f_tree_av($r->post_id, $level + 1);
      echo "</li>";
        } elseif ($r->Count==0) {
            echo "<li>" . "<a>". $r->post_title ."</a>". "\n";
        } else;
    }
    echo "</ul>\n";
?>

只需使用.=运算符，即$a=$a$a.=

---

你想附加什么？你想把它附加到什么？一个变量。例如：$ContentString1=$String1的缩写语法。$string2是$String1.=$string2；。这就是你要找的吗？不要在循环中回音，而是做$content。。。。；然后在准备好使用$content时输出它。@AvinVarghese

<?php
$content .= "<ul>\n";
    foreach($related as $r) {

        if ($r->Count > 0) {
            $content .= "<li>" . "<a>". $r->post_title ."</a>". "\n";
      f_tree_av($r->post_id, $level + 1);
      echo "</li>";
        } elseif ($r->Count==0) {
            $content .= "<li>" . "<a>". $r->post_title ."</a>". "\n";
        } else;
    }
   $content .= "</ul>\n";
?>

<?php
$content = "<ul>\n";
    foreach($related as $r) {

        if ($r->Count > 0) {
            $content .= "<li>" . "<a>". $r->post_title ."</a>". "\n";
      f_tree_av($r->post_id, $level + 1);
                  $content .= "</li>";
        } elseif ($r->Count==0) {
                        $content .= "<li>" . "<a>". $r->post_title ."</a>". "\n";
        } else;
    }
    echo $content . "</ul>\n";
?>