現在の投稿のカテゴリIDを取得するにはどうすればよいですか？

 function catName($cat_id) {
    $cat_id = (int) $cat_id;
    $category = &get_category($cat_id);
    return $category->name;
}
function catLink($cat_id) {
    $category = get_the_category();
    $category_link = get_category_link($cat_id);
    echo $category_link;
}

function catCustom() {
   $cats = get_the_category($post->ID);
    $parent = get_category($cats[1]->category_parent);
    if (is_wp_error($parent)){
        $cat = get_category($cats[0]);
      }
      else{
        $cat = $parent;
      }
    echo '<a href="'.get_category_link($cat).'">'.$cat->name.'</a>';    
}
 

USE <a href="<?php catLink(1); ?>"> <?php catName(1); ?>

function catName($cat_id) {
    $cat_id = (int) $cat_id;
    $category = &get_category($cat_id);
    return $category->name;
}
function catLink($cat_id) {
    $category = get_the_category();
    $category_link = get_category_link($cat_id);
    echo $category_link;
}

function catCustom() {
   $cats = get_the_category($post->ID);
    $parent = get_category($cats[1]->category_parent);
    if (is_wp_error($parent)){
        $cat = get_category($cats[0]);
      }
      else{
        $cat = $parent;
      }
    echo '<a href="'.get_category_link($cat).'">'.$cat->name.'</a>';    
}

USE <a href="<?php catLink(1); ?>"> <?php catName(1); ?>

get_the_category()関数を使用してカテゴリのデータを取得すると、オブジェクトの配列が返されるため、この$postcat[0]->term_id

 global $post;
$postcat = get_the_category( $post->ID );

// try print_r($postcat) ;  

if ( ! empty( $postcat ) ) {
    echo esc_html( $postcat[0]->name );   
}
 

この助けを願っています！

When you use get_the_category() function to get category's data, it return the array of object so you have to access category id by passing array key, like this $postcat[0]->term_id

global $post;
$postcat = get_the_category( $post->ID );

// try print_r($postcat) ;  

if ( ! empty( $postcat ) ) {
    echo esc_html( $postcat[0]->name );   
}

Hope this help!

質問者がカテゴリ名ではなくカテゴリID について質問するため、GovindKumarの回答が改善されました.カテゴリIDのオブジェクトのプロパティ名は「 cat_ID 」です.

 // get cat ID for general view
$postcat = get_the_category( $query->post->ID );
if ( ! empty( $postcat ) ) {
 echo $postcat[0]->cat_ID;
}
 

An improvement to Govind Kumar answer, as the asker askes about category ID, not the category name. The property name of the object for category ID is "cat_ID".

// get cat ID for general view
$postcat = get_the_category( $query->post->ID );
if ( ! empty( $postcat ) ) {
 echo $postcat[0]->cat_ID;
}

グローバル$post;
$postcat=get_the_category($post-> ID);
 if(！empty($postcat)){
 foreach($postcat as $nameCategory){
 echo $nameCategory->name. '';
         }
    }?>

global $post;
$postcat = get_the_category( $post->ID );
    if ( ! empty( $postcat ) ) {
       foreach ($postcat  as $nameCategory) {
           echo $nameCategory->name .' ';   
         }                                      
    }?>