{"author_url":"https://blog.hatena.ne.jp/perlcodesample/","version":"1.0","height":"190","type":"rich","provider_url":"https://hatena.blog","author_name":"perlcodesample","url":"https://perlcodesample.hatenadiary.jp/entry/20100219/1264257759","provider_name":"Hatena Blog","width":"100%","blog_title":"Perl\u5165\u9580\u30bc\u30df","image_url":null,"html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fperlcodesample.hatenadiary.jp%2Fentry%2F20100219%2F1264257759\" title=\"defined\u95a2\u6570 - \u5024\u304c\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u304b\u3092\u78ba\u8a8d\u3059\u308b - Perl\u5165\u9580\u30bc\u30df\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","categories":[],"published":"2010-02-19 23:42:39","blog_url":"https://perlcodesample.hatenadiary.jp/","title":"defined\u95a2\u6570 - \u5024\u304c\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u304b\u3092\u78ba\u8a8d\u3059\u308b","description":"Perl \u203a \u95a2\u6570 \u203a here \u5024\u304c\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u304b\u3092\u78ba\u8a8d\u3059\u308b\u306b\u306fdefined\u95a2\u6570\u3092\u4f7f\u7528\u3057\u307e\u3059\u3002 # \u5024\u304c\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u304b\u306e\u78ba\u8a8d $is_defined = defined $value; \u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u3068\u306f defined\u95a2\u6570\u3067\u5224\u5b9a\u3067\u304d\u308b\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u5024\u3068\u306f\u306a\u3093\u3067\u3057\u3087\u3046\u304b\u3002\u8003\u3048\u3066\u307f\u307e\u3057\u3087\u3046\u3002\u5909\u6570\u5ba3\u8a00\u3057\u305f\u5834\u5408\u306f\u3001\u4ee3\u5165\u306b\u3088\u308b\u521d\u671f\u5316\u3092\u884c\u308f\u306a\u304b\u3063\u305f\u5834\u5408\u306f\u672a\u5b9a\u7fa9\u3068\u306a\u308a\u307e\u3059\u3002 # \u5ba3\u8a00\u76f4\u5f8c\u306f\u672a\u5b9a\u7fa9 my $value; \u5024\u3092\u4ee3\u5165\u3059\u308b\u3068\u3001\u5024\u304c\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u72b6\u614b\u306b\u306a\u308a\u307e\u3059\u3002 # \u5024\u3092\u4ee3\u5165\u3057\u305f\u306e\u3067\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u72b6\u614b\u306b\u306a\u308b $value = 5; undef\u95a2\u6570\u3092\u4f7f\u3063\u3066\u3001\u672a\u5b9a\u7fa9\u5024\u304c\u4ee3\u5165\u3055\u308c\u308b\u3068\u5024\u306f\u672a\u5b9a\u7fa9\u306b\u306a\u2026"}