图片的alt属性对网站seo有重要的作用，我们在使用wordpress 建站添加文章或页面时，很多时候会忘记添加图片的alt信息。对于有很多图片的网站，每张图片都要再去设置alt，也是一件很繁琐的事情。今天我们讲解一下给wordpress 博客内容的图片自动添加图片的alt属性的方法。

实现的原理：判断上传的图片是否添加了alt属性，如果没有，会自动添加文章标题作为图片alt属性，以此来达到自动设置图片alt属性的功能。

切换到主题目录，打开functions.PHP 文件，添加如下代码：

Crayon-5c891d4c78fbc839900918" class="Crayon-Syntax Crayon-theme-classic Crayon-font-monaco Crayon-os-pc print-yes notranslate" data-settings=" minimize scroll-mouSEOver" style=" margin-top: 12px; margin-bottom: 12px; font-size: 12px !important; line-height: 15px !important;">

Crayon-toolbar" data-settings=" mouSEOver overlay hide delay" style="font-size: 12px !important;height: 18px !important; line-height: 18px !important;">Crayon-title">functions.PHP

Crayon-tools" style="font-size: 12px !important;height: 18px !important; line-height: 18px !important;">

Crayon-button Crayon-nums-button" title="Toggle Line Numbers">

Crayon-button-icon">

Crayon-button Crayon-plain-button" title="Toggle Plain Code">

Crayon-button-icon">

Crayon-button Crayon-wrap-button" title="Toggle Line Wrap">

Crayon-button-icon">

Crayon-button Crayon-expand-button" title="Expand Code">

Crayon-button-icon">

Crayon-button Crayon-copy-button" title="Copy">

Crayon-button-icon">

Crayon-button Crayon-popup-button" title="Open Code In New Window">

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Crayon-info" style="min-height: 16.8px !important; line-height: 16.8px !important;">

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post_title;
        $imgUrl = "<img\s[^>]*src=(\"??)([^\" >]*?)\\1[^>]*>";
        if(preg_match_all("/$imgUrl/siU",$imgalt,$matches,PREG_SET_ORDER)){
                if( !empty($matches) ){
                        for ($i=0; $i < count($matches); $i++){
                                $tag = $url = $matches[$i][0];
                                $judge = '/alt=/';
                                preg_match($judge,$tag,$match,PREG_OFFSET_CAPTURE);
                                if( count($match) < 1 )
                                $altURL = ' alt="'.$title.'" ';
                                $url = rtrim($url,'>');
                                $url .= $altURL.'>';
                                $imgalt = str_replace($tag,$url,$imgalt);
                        }
                }
        }
        return $imgalt;
}

add_filter( 'the_content','image_alt');

Crayon-main" style="">Crayon-table">Crayon-row">

Crayon-nums " data-settings="show">

Crayon-nums-content" style="font-size: 12px !important; line-height: 15px !important;">

Crayon-num" data-line="Crayon-5c891d4c78fbc839900918-1">1

Crayon-num Crayon-striped-num" data-line="Crayon-5c891d4c78fbc839900918-2">2

Crayon-num" data-line="Crayon-5c891d4c78fbc839900918-3">3

Crayon-num Crayon-striped-num" data-line="Crayon-5c891d4c78fbc839900918-4">4

Crayon-num" data-line="Crayon-5c891d4c78fbc839900918-5">5

Crayon-num Crayon-striped-num" data-line="Crayon-5c891d4c78fbc839900918-6">6

Crayon-num" data-line="Crayon-5c891d4c78fbc839900918-7">7

Crayon-num Crayon-striped-num" data-line="Crayon-5c891d4c78fbc839900918-8">8

Crayon-num" data-line="Crayon-5c891d4c78fbc839900918-9">9

Crayon-num Crayon-striped-num" data-line="Crayon-5c891d4c78fbc839900918-10">10

Crayon-num" data-line="Crayon-5c891d4c78fbc839900918-11">11

Crayon-num Crayon-striped-num" data-line="Crayon-5c891d4c78fbc839900918-12">12

Crayon-num" data-line="Crayon-5c891d4c78fbc839900918-13">13

Crayon-num Crayon-striped-num" data-line="Crayon-5c891d4c78fbc839900918-14">14

Crayon-num" data-line="Crayon-5c891d4c78fbc839900918-15">15

Crayon-num Crayon-striped-num" data-line="Crayon-5c891d4c78fbc839900918-16">16

Crayon-num" data-line="Crayon-5c891d4c78fbc839900918-17">17

Crayon-num Crayon-striped-num" data-line="Crayon-5c891d4c78fbc839900918-18">18

Crayon-num" data-line="Crayon-5c891d4c78fbc839900918-19">19

Crayon-num Crayon-striped-num" data-line="Crayon-5c891d4c78fbc839900918-20">20

Crayon-num" data-line="Crayon-5c891d4c78fbc839900918-21">21

Crayon-num Crayon-striped-num" data-line="Crayon-5c891d4c78fbc839900918-22">22

Crayon-num" data-line="Crayon-5c891d4c78fbc839900918-23">23

Crayon-code">

Crayon-pre" style="font-size: 12px !important; line-height: 15px !important; -moz-tab-size:4; -o-tab-size:4; -webkit-tab-size:4; tab-size:4;">

Crayon-line" id="Crayon-5c891d4c78fbc839900918-1">Crayon-c">//图片添加alt属性

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Crayon-line" id="Crayon-5c891d4c78fbc839900918-17">Crayon-h">Crayon-sy">}

Crayon-line Crayon-striped-line" id="Crayon-5c891d4c78fbc839900918-18">Crayon-h">Crayon-sy">}

Crayon-line" id="Crayon-5c891d4c78fbc839900918-19">Crayon-h">Crayon-sy">}

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图片ALT