先日の記事で、階層カテゴリーの親子関係の判定のために「最上層のIDを取得する方法」について書いたわけですが。
めげずに調べていたところ、こちらの記事でもっと簡潔な方法がが紹介されていました。

WebTecNote – [WP]Category, Tag and Taxonomy Functions

ついでに、MovableTypeの場合も併せてご紹介します。
MovableTypeと比較するため、今回はWordPressの方は関数化していません。

WordPressの場合

<?php $catArr = get_the_category($post->ID);<br /> $flg = false;<br /> foreach($catArr as $var) {<br /> $cat = $var->cat_ID;<br /> if(cat_is_ancestor_of([親カテゴリーのID], (int) $cat)) $flg = true;<br /> }<br /> if($flg) echo “<span style="color: green;"">この記事は[親カテゴリー名]に含まれています</span>“”;</p> </div></div> <div class="wp-block-group has-global-padding is-layout-constrained wp-block-group-is-layout-constrained"> <nav aria-label="Posts" class="wp-block-group is-content-justification-space-between is-nowrap is-layout-flex wp-container-core-group-is-layout-10 wp-block-group-is-layout-flex" style="padding-top:var(--wp--preset--spacing--40);padding-bottom:var(--wp--preset--spacing--40)"><div class="post-navigation-link-previous wp-block-post-navigation-link"><span class="wp-block-post-navigation-link__arrow-previous is-arrow-chevron" aria-hidden="true">«</span><a href="https://webbingstudio.com/entry-342/" rel="prev"><span class="post-navigation-link__label">前:</span> <span class="post-navigation-link__title">WordPressで最上層のカテゴリーを取得するTips</span></a></div> <div class="post-navigation-link-next wp-block-post-navigation-link"><a href="https://webbingstudio.com/entry-345/" rel="next"><span class="post-navigation-link__label">次:</span> <span class="post-navigation-link__title">ドメインが失効してしまった／(＾o＾)＼</span></a><span class="wp-block-post-navigation-link__arrow-next is-arrow-chevron" aria-hidden="true">»</span></div></nav> </div> </div> <div class="wp-block-column is-layout-flow wp-block-column-is-layout-flow" style="flex-basis:30%"><aside class="wp-block-template-part"> <div class="wp-block-group is-layout-flow wp-container-core-group-is-layout-15 wp-block-group-is-layout-flow" style="padding-right:0;padding-left:0"> <div class="wp-block-group has-global-padding is-layout-constrained wp-block-group-is-layout-constrained" style="margin-top:0;margin-bottom:0"><div class="wp-block-avatar"><img alt='うぇびんのアバター' src='https://secure.gravatar.com/avatar/e5f1b4568c55a9ee59afb5523a2ef307?s=100&d=mm&r=g' srcset='https://secure.gravatar.com/avatar/e5f1b4568c55a9ee59afb5523a2ef307?s=200&d=mm&r=g 2x' class='avatar avatar-100 photo wp-block-avatar__image' height='100' width='100' style="border-radius:50%;" decoding='async'/></div> <div class="wp-block-group is-vertical is-layout-flex wp-container-core-group-is-layout-12 wp-block-group-is-layout-flex"> <h2 class="wp-block-heading" style="font-size:clamp(1.039rem, 1.039rem + ((1vw - 0.2rem) * 0.935), 1.6rem);">About me</h2> <div style="font-size:clamp(0.875rem, 0.875rem + ((1vw - 0.2rem) * 0.625), 1.25rem);font-style:normal;font-weight:600;" class="wp-block-post-author-name">うぇびん</div> <div class="wp-block-post-author-biography has-small-font-size">愛知県豊橋市に住んでいる、荒ぶるウェブおばさん。Web製作者、コーダー、CMSのテーマ作る係。フリーランス15年→札幌のビットスター所属。 Web developer, Coder, CMS Themer. Bitstar Inc.</div></div> </div> <hr class="wp-block-separator has-text-color has-contrast-color has-alpha-channel-opacity has-contrast-background-color has-background is-style-wide"/> <div class="wp-block-group has-global-padding is-layout-constrained wp-container-core-group-is-layout-14 wp-block-group-is-layout-constrained"> <h2 class="wp-block-heading" style="font-size:clamp(1.039rem, 1.039rem + ((1vw - 0.2rem) * 0.935), 1.6rem);">Tags</h2> <p class="is-style-default wp-block-tag-cloud"><a href="https://webbingstudio.com/tag/ablogcms/" class="tag-cloud-link tag-link-9 tag-link-position-1" style="font-size: 24pt;" aria-label="ablogcms (124個の項目)">ablogcms</a> <a href="https://webbingstudio.com/tag/basercms/" class="tag-cloud-link tag-link-44 tag-link-position-2" style="font-size: 9.0566037735849pt;" aria-label="baserCMS (12個の項目)">baserCMS</a> <a href="https://webbingstudio.com/tag/concrete5/" class="tag-cloud-link tag-link-62 tag-link-position-3" style="font-size: 8pt;" 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