{"id":322,"date":"2024-10-07T13:44:39","date_gmt":"2024-10-07T05:44:39","guid":{"rendered":"https:\/\/www.cgh0610.cn\/?p=322"},"modified":"2024-10-07T13:53:20","modified_gmt":"2024-10-07T05:53:20","slug":"php7-4%e5%90%8e-%e4%b8%8e-%e7%9a%84%e5%8c%ba%e5%88%ab","status":"publish","type":"post","link":"https:\/\/www.cgh0610.cn\/?p=322","title":{"rendered":"PHP7.4\u540e ?? \u4e0e ?:\u7684\u533a\u522b"},"content":{"rendered":"<p>PHP7.4\u7248\u672c\u53d1\u5e03\u540e\uff0c\u65b0\u589e\u7a7a\uff08NULL\uff09\u5408\u5e76\u8fd0\u7b97\u7b26\uff1f\uff1f\u7684\u8bed\u6cd5\u7cd6\uff0c\u5982\u679c\u53d8\u91cf\u5b58\u5728\u4e14\u503c\u4e0d\u4e3a NULL\uff0c \u5b83\u5c31\u4f1a\u8fd4\u56de\u81ea\u8eab\u7684\u503c\uff0c\u5426\u5219\u8fd4\u56de\u5b83\u7684\u7b2c\u4e8c\u4e2a\u64cd\u4f5c\u6570\u3002\u4e0e\u4ee5\u524d\u5c31\u5b58\u5728\u7684\u7b80\u5199\u7684\u6761\u4ef6\u8fd0\u7b97\u7b26\uff1f\uff1a\u6709\u70b9\u7c7b\u4f3c\uff1b<\/p>\n<p>\uff1f\uff1f\u4e0e\uff1f\uff1a\u5bf9\u6bd4<\/p>\n<pre><code class=\"php\">\n<span class=\"katex math inline\">a = 1;<\/span>b = <span class=\"katex math inline\">a ?: 2;\/\/<\/span>a \u4e3atrue\u5c31\u8fd4\u56de\u81ea\u8eab\uff0c\u5426\u8005\u8fd4\u56de\u7b2c\u4e8c\u4e2a\u64cd\u4f5c\u6570\n<span class=\"katex math inline\">c =<\/span>a ?? 2;\/\/<span class=\"katex math inline\">a\u4e0d\u4e3anull\u5c31\u8fd4\u56de\u81ea\u8eab\uff0c\u5426\u8005\u8fd4\u56de\u7b2c\u4e8c\u4e2a\u64cd\u4f5c\u6570\n\/\/ dd(<\/span>b,<span class=\"katex math inline\">c);\/\/ int(1)  int(1)<\/span>a = 0;\n<span class=\"katex math inline\">b =<\/span>a ?: 2;\/\/<span class=\"katex math inline\">a \u4e3atrue\u5c31\u8fd4\u56de\u81ea\u8eab\uff0c\u5426\u8005\u8fd4\u56de\u7b2c\u4e8c\u4e2a\u64cd\u4f5c\u6570<\/span>c = <span class=\"katex math inline\">a ?? 2;\/\/<\/span>a\u4e0d\u4e3anull\u5c31\u8fd4\u56de\u81ea\u8eab\uff0c\u5426\u8005\u8fd4\u56de\u7b2c\u4e8c\u4e2a\u64cd\u4f5c\u6570\n\/\/ dd(<span class=\"katex math inline\">b,<\/span>c);\/\/ int(2)  int(0)\n\n<span class=\"katex math inline\">a = null;<\/span>b = <span class=\"katex math inline\">a ?: 2;\/\/<\/span>a \u4e3atrue\u5c31\u8fd4\u56de\u81ea\u8eab\uff0c\u5426\u8005\u8fd4\u56de\u7b2c\u4e8c\u4e2a\u64cd\u4f5c\u6570\n<span class=\"katex math inline\">c =<\/span>a ?? 2;\/\/<span class=\"katex math inline\">a\u4e0d\u4e3anull\u5c31\u8fd4\u56de\u81ea\u8eab\uff0c\u5426\u8005\u8fd4\u56de\u7b2c\u4e8c\u4e2a\u64cd\u4f5c\u6570\ndd(<\/span>b,$c);\/\/ int(2)  int(2)\n\n<\/code><\/pre>\n<p>\u7a7a\u5408\u5e76\u8fd0\u7b97\u8d4b\u503c\u7b26 \uff1f\uff1f=<\/p>\n<p><code>$name = $name ?? 'john'<\/code><br \/>\n\u53ef\u4ee5\u7b80\u5199\u6210<br \/>\n<code>$name ??= 'john'<\/code><\/p>\n","protected":false},"excerpt":{"rendered":"<p>PHP7.4\u7248\u672c\u53d1\u5e03\u540e\uff0c\u65b0\u589e\u7a7a\uff08NULL\uff09\u5408\u5e76\u8fd0\u7b97\u7b26\uff1f\uff1f\u7684\u8bed\u6cd5\u7cd6\uff0c\u5982\u679c\u53d8\u91cf\u5b58\u5728\u4e14\u503c\u4e0d\u4e3a NULL\uff0c \u5b83\u5c31\u4f1a\u8fd4\u56de &hellip; <a href=\"https:\/\/www.cgh0610.cn\/?p=322\" class=\"more-link\">\u7ee7\u7eed\u9605\u8bfb<span class=\"screen-reader-text\">PHP7.4\u540e ?? \u4e0e ?:\u7684\u533a\u522b<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"aside","meta":[],"categories":[65,38],"tags":[],"_links":{"self":[{"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=\/wp\/v2\/posts\/322"}],"collection":[{"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=322"}],"version-history":[{"count":3,"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=\/wp\/v2\/posts\/322\/revisions"}],"predecessor-version":[{"id":326,"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=\/wp\/v2\/posts\/322\/revisions\/326"}],"wp:attachment":[{"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=322"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=322"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.cgh0610.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=322"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}