{"id":75602,"date":"2024-03-20T15:58:51","date_gmt":"2024-03-20T06:58:51","guid":{"rendered":"https:\/\/www.silicloud.com\/ja\/blog\/c%e3%81%aeunion%e3%81%a8%e3%81%af\/"},"modified":"2025-08-11T12:50:14","modified_gmt":"2025-08-11T03:50:14","slug":"c%e3%81%aeunion%e3%81%a8%e3%81%af","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/ja\/blog\/c%e3%81%aeunion%e3%81%a8%e3%81%af\/","title":{"rendered":"C++\u306eunion\u3068\u306f"},"content":{"rendered":"<p>C++\u306eunion\u306f\u3001\u540c\u3058\u30e1\u30e2\u30ea\u4f4d\u7f6e\u306b\u7570\u306a\u308b\u30c7\u30fc\u30bf\u578b\u3092\u683c\u7d0d\u3067\u304d\u308b\u7279\u6b8a\u306a\u30c7\u30fc\u30bf\u69cb\u9020\u3067\u3059\u3002<\/p>\n<ol>\n<li>\u30e1\u30e2\u30ea\u30fc\u306e\u7bc0\u7d04\uff1aunion\u3092\u4f7f\u3046\u3053\u3068\u3067\u3001\u5404\u30e1\u30f3\u30d0\u30fc\u306b\u30e1\u30e2\u30ea\u30fc\u3092\u5272\u308a\u5f53\u3066\u308b\u306e\u3067\u306f\u306a\u304f\u3001\u305d\u306e\u3046\u3061\u306e1\u3064\u306e\u30e1\u30f3\u30d0\u30fc\u306b\u306e\u307f\u30e1\u30e2\u30ea\u30fc\u3092\u5272\u308a\u5f53\u3066\u308b\u3053\u3068\u304c\u3067\u304d\u308b\u306e\u3067\u3001\u30e1\u30e2\u30ea\u30fc\u306e\u7bc0\u7d04\u306b\u306a\u308a\u307e\u3059\u3002<\/li>\n<li>\u30c7\u30fc\u30bf\u5171\u6709\uff1aunion\u306e\u30e1\u30f3\u30d0\u306f\u540c\u3058\u30e1\u30e2\u30ea\u3092\u5171\u6709\u3057\u3066\u3044\u307e\u3059\u3002\u3064\u307e\u308a\u3001\u540c\u6642\u306b1\u3064\u306e\u30e1\u30f3\u30d0\u306e\u5024\u306e\u307f\u683c\u7d0d\u3067\u304d\u307e\u3059\u30021\u3064\u306e\u30e1\u30f3\u30d0\u306b\u5024\u3092\u4ee3\u5165\u3059\u308b\u3068\u3001\u524d\u306b\u683c\u7d0d\u3055\u308c\u305f\u30e1\u30f3\u30d0\u306e\u5024\u304c\u4e0a\u66f8\u304d\u3055\u308c\u307e\u3059\u3002<\/li>\n<li>\u30c7\u30fc\u30bf\u578b\u5909\u63db\uff1aunion\u3092\u4f7f\u3063\u3066\u30c7\u30fc\u30bf\u578b\u5909\u63db\u304c\u3067\u304d\u307e\u3059\u3002\u4f8b\u3048\u3070\u3001union\u306e\u30e1\u30f3\u30d0\u306e1\u3064\u306bfloat\u578b\u3092\u683c\u7d0d\u3057\u3066\u304a\u3044\u3066\u3001int\u578b\u3068\u3057\u3066\u8aad\u307f\u53d6\u308b\u306a\u3069<\/li>\n<\/ol>\n<p>\u6b21\u306b\u3001union \u306e\u4f7f\u3044\u65b9\u306b\u3064\u3044\u3066\u4f8b\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n<pre class=\"post-pre\"><code>#include &lt;iostream&gt;\r\nusing namespace std;\r\n\r\nunion Data {\r\n   int i;\r\n   float f;\r\n   char str[20];\r\n};\r\n\r\nint main() {\r\n   Data data;\r\n   \r\n   cout &lt;&lt; \"Memory size occupied by data : \" &lt;&lt; sizeof(data) &lt;&lt; endl;\r\n\r\n   data.i = 10;\r\n   cout &lt;&lt; \"data.i : \" &lt;&lt; data.i &lt;&lt; endl;\r\n   \r\n   data.f = 220.5;\r\n   cout &lt;&lt; \"data.f : \" &lt;&lt; data.f &lt;&lt; endl;\r\n   \r\n   strcpy(data.str, \"C++ Programming\");\r\n   cout &lt;&lt; \"data.str : \" &lt;&lt; data.str &lt;&lt; endl;\r\n\r\n   return 0;\r\n}\r\n<\/code><\/pre>\n<p>\u5f7c\u5973\u306f\u79c1\u306b\u672c\u3092\u8fd4\u3055\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044<\/p>\n<pre class=\"post-pre\"><code>Memory size occupied by data : 20\r\ndata.i : 10\r\ndata.f : 220.5\r\ndata.str : C++ Programming\r\n<\/code><\/pre>\n<p>\u4e0a\u8a18\u306e\u4f8b\u3067\u306f\u3001Data\u3068\u3044\u3046\u30e6\u30cb\u30aa\u30f3\u3092\u5b9a\u7fa9\u3057\u3066\u3044\u307e\u3059\u3002\u3053\u306e\u30e6\u30cb\u30aa\u30f3\u306f\u3001i\uff08\u6574\u6570\u578b\uff09\u3001f\uff08\u6d6e\u52d5\u5c0f\u6570\u70b9\u6570\u578b\uff09\u3001str\uff08\u6587\u5b57\u914d\u5217\u578b\uff09\u3068\u3044\u30463\u3064\u306e\u30e1\u30f3\u30d0\u30fc\u5909\u6570\u3092\u6301\u3063\u3066\u3044\u307e\u3059\u3002\u3054\u89a7\u306e\u3068\u304a\u308a\u3001\u3053\u306e3\u3064\u306e\u30e1\u30f3\u30d0\u30fc\u5909\u6570\u306f\u540c\u4e00\u306e\u30e1\u30e2\u30ea\u9818\u57df\u3092\u5171\u6709\u3057\u3066\u304a\u308a\u3001\u305d\u306e\u305f\u3081\u3001\u305d\u306e\u3046\u30611\u3064\u306e\u5024\u306e\u307f\u3092\u683c\u7d0d\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002main\u95a2\u6570\u3067\u306f\u3001\u6574\u6570\u3001\u6d6e\u52d5\u5c0f\u6570\u70b9\u6570\u3001\u6587\u5b57\u5217\u3092\u305d\u308c\u305e\u308c\u30e6\u30cb\u30aa\u30f3\u306e\u30e1\u30f3\u30d0\u30fc\u5909\u6570\u306b\u5272\u308a\u5f53\u3066\u3001\u305d\u306e\u5024\u3092\u51fa\u529b\u3057\u307e\u3059\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>C++\u306eunion\u306f\u3001\u540c\u3058\u30e1\u30e2\u30ea\u4f4d\u7f6e\u306b\u7570\u306a\u308b\u30c7\u30fc\u30bf\u578b\u3092\u683c\u7d0d\u3067\u304d\u308b\u7279\u6b8a\u306a\u30c7\u30fc\u30bf\u69cb\u9020\u3067\u3059\u3002 \u30e1\u30e2\u30ea\u30fc\u306e\u7bc0\u7d04\uff1aunion\u3092\u4f7f\u3046\u3053\u3068\u3067\u3001\u5404\u30e1\u30f3\u30d0\u30fc\u306b\u30e1\u30e2\u30ea\u30fc\u3092\u5272\u308a\u5f53\u3066\u308b\u306e\u3067\u306f\u306a\u304f\u3001\u305d\u306e\u3046\u3061\u306e1\u3064\u306e\u30e1\u30f3\u30d0\u30fc\u306b\u306e\u307f\u30e1\u30e2\u30ea\u30fc\u3092\u5272\u308a\u5f53\u3066 [&hellip;]<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[26,61],"class_list":["post-75602","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-26","tag-61"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v21.5 (Yoast SEO v21.5) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>C++\u306eunion\u3068\u306f - Blog - Silicon Cloud<\/title>\n<meta name=\"description\" content=\"C++\u306eunion\u3068\u306f\u3092\u5206\u304b\u308a\u3084\u3059\u304f\u89e3\u8aac\u3002\u5b9f\u8df5\u7684\u306a\u4f8b\u3068\u30b3\u30fc\u30c9\u3001\u6ce8\u610f\u70b9\u3092\u542b\u3081\u3066\u521d\u5fc3\u8005\u306b\u3082\u7406\u89e3\u3067\u304d\u308b\u3088\u3046\u8aac\u660e\u3057\u307e\u3059\u3002\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.silicloud.com\/ja\/blog\/c\u306eunion\u3068\u306f\/\" \/>\n<meta property=\"og:locale\" content=\"ja_JP\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"C++\u306eunion\u3068\u306f\" \/>\n<meta property=\"og:description\" content=\"C++\u306eunion\u3068\u306f\u3092\u5206\u304b\u308a\u3084\u3059\u304f\u89e3\u8aac\u3002\u5b9f\u8df5\u7684\u306a\u4f8b\u3068\u30b3\u30fc\u30c9\u3001\u6ce8\u610f\u70b9\u3092\u542b\u3081\u3066\u521d\u5fc3\u8005\u306b\u3082\u7406\u89e3\u3067\u304d\u308b\u3088\u3046\u8aac\u660e\u3057\u307e\u3059\u3002\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.silicloud.com\/ja\/blog\/c\u306eunion\u3068\u306f\/\" \/>\n<meta property=\"og:site_name\" content=\"Blog - Silicon Cloud\" \/>\n<meta property=\"article:published_time\" content=\"2024-03-20T06:58:51+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2025-08-11T03:50:14+00:00\" \/>\n<meta name=\"author\" content=\"\u685c, \u6625\u6a39\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"\u57f7\u7b46\u8005\" \/>\n\t<meta name=\"twitter:data1\" content=\"\u685c, \u6625\u6a39\" \/>\n\t<meta name=\"twitter:label2\" content=\"\u63a8\u5b9a\u8aad\u307f\u53d6\u308a\u6642\u9593\" \/>\n\t<meta name=\"twitter:data2\" content=\"3\u5206\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.silicloud.com\/ja\/blog\/c%e3%81%aeunion%e3%81%a8%e3%81%af\/\",\"url\":\"https:\/\/www.silicloud.com\/ja\/blog\/c%e3%81%aeunion%e3%81%a8%e3%81%af\/\",\"name\":\"C++\u306eunion\u3068\u306f - Blog - Silicon Cloud\",\"isPartOf\":{\"@id\":\"https:\/\/www.silicloud.com\/ja\/blog\/#website\"},\"datePublished\":\"2024-03-20T06:58:51+00:00\",\"dateModified\":\"2025-08-11T03:50:14+00:00\",\"author\":{\"@id\":\"https:\/\/www.silicloud.com\/ja\/blog\/#\/schema\/person\/ff22288af1a5455571aff7586b0fb341\"},\"description\":\"C++\u306eunion\u3068\u306f\u3092\u5206\u304b\u308a\u3084\u3059\u304f\u89e3\u8aac\u3002\u5b9f\u8df5\u7684\u306a\u4f8b\u3068\u30b3\u30fc\u30c9\u3001\u6ce8\u610f\u70b9\u3092\u542b\u3081\u3066\u521d\u5fc3\u8005\u306b\u3082\u7406\u89e3\u3067\u304d\u308b\u3088\u3046\u8aac\u660e\u3057\u307e\u3059\u3002\",\"breadcrumb\":{\"@id\":\"https:\/\/www.silicloud.com\/ja\/blog\/c%e3%81%aeunion%e3%81%a8%e3%81%af\/#breadcrumb\"},\"inLanguage\":\"ja\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.silicloud.com\/ja\/blog\/c%e3%81%aeunion%e3%81%a8%e3%81%af\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.silicloud.com\/ja\/blog\/c%e3%81%aeunion%e3%81%a8%e3%81%af\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"\u9996\u9875\",\"item\":\"https:\/\/www.silicloud.com\/ja\/blog\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"C++\u306eunion\u3068\u306f\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.silicloud.com\/ja\/blog\/#website\",\"url\":\"https:\/\/www.silicloud.com\/ja\/blog\/\",\"name\":\"Blog - Silicon Cloud\",\"description\":\"\",\"inLanguage\":\"ja\"},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.silicloud.com\/ja\/blog\/#\/schema\/person\/ff22288af1a5455571aff7586b0fb341\",\"name\":\"\u685c, \u6625\u6a39\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"ja\",\"@id\":\"https:\/\/www.silicloud.com\/ja\/blog\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/cee48863f3d4fd7fef222498f3e71b82312aee42b7257a2dbde56394ca4e19de?s=96&d=mm&r=g\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/cee48863f3d4fd7fef222498f3e71b82312aee42b7257a2dbde56394ca4e19de?s=96&d=mm&r=g\",\"caption\":\"\u685c, \u6625\u6a39\"},\"url\":\"https:\/\/www.silicloud.com\/ja\/blog\/author\/sakuraharuki\/\"},{\"@type\":\"ImageObject\",\"inLanguage\":\"ja\",\"@id\":\"https:\/\/www.silicloud.com\/ja\/blog\/c%e3%81%aeunion%e3%81%a8%e3%81%af\/#local-main-organization-logo\",\"url\":\"\",\"contentUrl\":\"\",\"caption\":\"Blog - Silicon Cloud\"}]}<\/script>\n<!-- \/ Yoast SEO Premium plugin. -->","yoast_head_json":{"title":"C++\u306eunion\u3068\u306f - Blog - Silicon Cloud","description":"C++\u306eunion\u3068\u306f\u3092\u5206\u304b\u308a\u3084\u3059\u304f\u89e3\u8aac\u3002\u5b9f\u8df5\u7684\u306a\u4f8b\u3068\u30b3\u30fc\u30c9\u3001\u6ce8\u610f\u70b9\u3092\u542b\u3081\u3066\u521d\u5fc3\u8005\u306b\u3082\u7406\u89e3\u3067\u304d\u308b\u3088\u3046\u8aac\u660e\u3057\u307e\u3059\u3002","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.silicloud.com\/ja\/blog\/c\u306eunion\u3068\u306f\/","og_locale":"ja_JP","og_type":"article","og_title":"C++\u306eunion\u3068\u306f","og_description":"C++\u306eunion\u3068\u306f\u3092\u5206\u304b\u308a\u3084\u3059\u304f\u89e3\u8aac\u3002\u5b9f\u8df5\u7684\u306a\u4f8b\u3068\u30b3\u30fc\u30c9\u3001\u6ce8\u610f\u70b9\u3092\u542b\u3081\u3066\u521d\u5fc3\u8005\u306b\u3082\u7406\u89e3\u3067\u304d\u308b\u3088\u3046\u8aac\u660e\u3057\u307e\u3059\u3002","og_url":"https:\/\/www.silicloud.com\/ja\/blog\/c\u306eunion\u3068\u306f\/","og_site_name":"Blog - Silicon Cloud","article_published_time":"2024-03-20T06:58:51+00:00","article_modified_time":"2025-08-11T03:50:14+00:00","author":"\u685c, \u6625\u6a39","twitter_card":"summary_large_image","twitter_misc":{"\u57f7\u7b46\u8005":"\u685c, \u6625\u6a39","\u63a8\u5b9a\u8aad\u307f\u53d6\u308a\u6642\u9593":"3\u5206"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/www.silicloud.com\/ja\/blog\/c%e3%81%aeunion%e3%81%a8%e3%81%af\/","url":"https:\/\/www.silicloud.com\/ja\/blog\/c%e3%81%aeunion%e3%81%a8%e3%81%af\/","name":"C++\u306eunion\u3068\u306f - Blog - Silicon Cloud","isPartOf":{"@id":"https:\/\/www.silicloud.com\/ja\/blog\/#website"},"datePublished":"2024-03-20T06:58:51+00:00","dateModified":"2025-08-11T03:50:14+00:00","author":{"@id":"https:\/\/www.silicloud.com\/ja\/blog\/#\/schema\/person\/ff22288af1a5455571aff7586b0fb341"},"description":"C++\u306eunion\u3068\u306f\u3092\u5206\u304b\u308a\u3084\u3059\u304f\u89e3\u8aac\u3002\u5b9f\u8df5\u7684\u306a\u4f8b\u3068\u30b3\u30fc\u30c9\u3001\u6ce8\u610f\u70b9\u3092\u542b\u3081\u3066\u521d\u5fc3\u8005\u306b\u3082\u7406\u89e3\u3067\u304d\u308b\u3088\u3046\u8aac\u660e\u3057\u307e\u3059\u3002","breadcrumb":{"@id":"https:\/\/www.silicloud.com\/ja\/blog\/c%e3%81%aeunion%e3%81%a8%e3%81%af\/#breadcrumb"},"inLanguage":"ja","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.silicloud.com\/ja\/blog\/c%e3%81%aeunion%e3%81%a8%e3%81%af\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/www.silicloud.com\/ja\/blog\/c%e3%81%aeunion%e3%81%a8%e3%81%af\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"\u9996\u9875","item":"https:\/\/www.silicloud.com\/ja\/blog\/"},{"@type":"ListItem","position":2,"name":"C++\u306eunion\u3068\u306f"}]},{"@type":"WebSite","@id":"https:\/\/www.silicloud.com\/ja\/blog\/#website","url":"https:\/\/www.silicloud.com\/ja\/blog\/","name":"Blog - Silicon Cloud","description":"","inLanguage":"ja"},{"@type":"Person","@id":"https:\/\/www.silicloud.com\/ja\/blog\/#\/schema\/person\/ff22288af1a5455571aff7586b0fb341","name":"\u685c, \u6625\u6a39","image":{"@type":"ImageObject","inLanguage":"ja","@id":"https:\/\/www.silicloud.com\/ja\/blog\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/cee48863f3d4fd7fef222498f3e71b82312aee42b7257a2dbde56394ca4e19de?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/cee48863f3d4fd7fef222498f3e71b82312aee42b7257a2dbde56394ca4e19de?s=96&d=mm&r=g","caption":"\u685c, \u6625\u6a39"},"url":"https:\/\/www.silicloud.com\/ja\/blog\/author\/sakuraharuki\/"},{"@type":"ImageObject","inLanguage":"ja","@id":"https:\/\/www.silicloud.com\/ja\/blog\/c%e3%81%aeunion%e3%81%a8%e3%81%af\/#local-main-organization-logo","url":"","contentUrl":"","caption":"Blog - Silicon Cloud"}]}},"_links":{"self":[{"href":"https:\/\/www.silicloud.com\/ja\/blog\/wp-json\/wp\/v2\/posts\/75602","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.silicloud.com\/ja\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.silicloud.com\/ja\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.silicloud.com\/ja\/blog\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/www.silicloud.com\/ja\/blog\/wp-json\/wp\/v2\/comments?post=75602"}],"version-history":[{"count":1,"href":"https:\/\/www.silicloud.com\/ja\/blog\/wp-json\/wp\/v2\/posts\/75602\/revisions"}],"predecessor-version":[{"id":181375,"href":"https:\/\/www.silicloud.com\/ja\/blog\/wp-json\/wp\/v2\/posts\/75602\/revisions\/181375"}],"wp:attachment":[{"href":"https:\/\/www.silicloud.com\/ja\/blog\/wp-json\/wp\/v2\/media?parent=75602"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.silicloud.com\/ja\/blog\/wp-json\/wp\/v2\/categories?post=75602"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.silicloud.com\/ja\/blog\/wp-json\/wp\/v2\/tags?post=75602"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}