{"blog_url":"https://memo.sugyan.com/","height":"190","type":"rich","html":"<iframe src=\"https://hatenablog-parts.com/embed?url=https%3A%2F%2Fmemo.sugyan.com%2Fentry%2F20101006%2F1286371100\" title=\"map\u3057\u305f\u7d50\u679c\u304cundef\u306e\u3082\u306e\u3092\u9664\u3044\u305f\u914d\u5217\u3092\u5f97\u308b - \u3059\u304e\u3083\u30fc\u3093\u30e1\u30e2\" class=\"embed-card embed-blogcard\" scrolling=\"no\" frameborder=\"0\" style=\"display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;\"></iframe>","image_url":null,"provider_url":"https://hatena.blog","url":"https://memo.sugyan.com/entry/20101006/1286371100","categories":["Perl"],"version":"1.0","title":"map\u3057\u305f\u7d50\u679c\u304cundef\u306e\u3082\u306e\u3092\u9664\u3044\u305f\u914d\u5217\u3092\u5f97\u308b","author_url":"https://blog.hatena.ne.jp/sugyan/","width":"100%","published":"2010-10-06 22:18:20","provider_name":"Hatena Blog","blog_title":"\u3059\u304e\u3083\u30fc\u3093\u30e1\u30e2","description":"\u77e5\u3089\u306a\u304b\u3063\u305f\u3002\u3002 my @arr = ( { key => 1 }, { key => 2 }, { key => undef }, { key => 3 } ); \u306e\u3088\u3046\u306a\u30c7\u30fc\u30bf\u306b\u5bfe\u3057\u3001\u5168\u8981\u7d20\u306e\"key\"\u306b\u5bfe\u5fdc\u3059\u308b\u5024\u3092\u53d6\u308a\u51fa\u3057\u305fmap\u3092\u5f97\u308b\u3068 print \"$_\\n\" for map { $_->{key} } @arr; 1 2 Use of uninitialized value $_ in concatenation (.) or string ... 3\u3068\u306a\u308b\u3002map\u306e\u7d50\u679c\u306fundef\u3082\u542b\u30804\u8981\u7d20\u306e\u914d\u5217\u3068\u3044\u3046\u3053\u3068\u306b\u306a\u308b\u3002 \u3053\u3053\u304b\u3089undef\u306e\u3084\u3064\u3092\u9664\u304d\u305f\u3044\u3001\u3068\u3044\u3046\u3068\u304d\u3001\u4eca\u307e\u3067\u305a\u3063\u3068 \u2026","author_name":"sugyan"}