{"id":351,"date":"2014-12-30T18:19:40","date_gmt":"2014-12-30T17:19:40","guid":{"rendered":"http:\/\/www.valcon.it\/pascal\/?p=351"},"modified":"2014-12-30T18:26:25","modified_gmt":"2014-12-30T17:26:25","slug":"alternativa-ciondolante","status":"publish","type":"post","link":"https:\/\/www.valcon.it\/pascal\/alternativa-ciondolante\/","title":{"rendered":"Alternativa ciondolante"},"content":{"rendered":"<p>Considera <em>attentamente<\/em>\u00a0i due diagrammi di flusso e le\u00a0codifiche corrispondenti<\/p>\n<table>\n<tbody>\n<tr valign=\"top\">\n<td><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-73 size-full\" src=\"http:\/\/www.valcon.it\/pascal\/wp-content\/uploads\/ifcio1.png\" alt=\"ifcio1\" width=\"261\" height=\"469\" srcset=\"https:\/\/www.valcon.it\/pascal\/wp-content\/uploads\/ifcio1.png 261w, https:\/\/www.valcon.it\/pascal\/wp-content\/uploads\/ifcio1-83x150.png 83w, https:\/\/www.valcon.it\/pascal\/wp-content\/uploads\/ifcio1-167x300.png 167w\" sizes=\"(max-width: 261px) 100vw, 261px\" \/><\/td>\n<td>\n<pre>If A > 0 Then\r\n \u00a0 Begin\r\n\u00a0 \u00a0 \u00a0 If B > 0 Then\r\n \u00a0 \u00a0 \u00a0 \u00a0 Begin\r\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Istr11;\r\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Istr12;\r\n \u00a0 \u00a0 \u00a0 \u00a0 End\r\n  \u00a0 \u00a0 Else\r\n \u00a0 \u00a0 \u00a0 \u00a0 Begin\r\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Istr21;\r\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Istr22;\r\n \u00a0 \u00a0 \u00a0 \u00a0 End;\r\n\u00a0  End;<\/pre>\n<\/td>\n<\/tr>\n<tr valign=\"top\">\n<td><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter wp-image-74 size-full\" src=\"http:\/\/www.valcon.it\/pascal\/wp-content\/uploads\/ifcio2.png\" alt=\"ifcio2\" width=\"268\" height=\"469\" srcset=\"https:\/\/www.valcon.it\/pascal\/wp-content\/uploads\/ifcio2.png 268w, https:\/\/www.valcon.it\/pascal\/wp-content\/uploads\/ifcio2-86x150.png 86w, https:\/\/www.valcon.it\/pascal\/wp-content\/uploads\/ifcio2-171x300.png 171w\" sizes=\"(max-width: 268px) 100vw, 268px\" \/><\/td>\n<td>\n<pre>If A > 0 Then\r\n\u00a0  Begin\r\n\u00a0 \u00a0 \u00a0 If B > 0 Then\r\n\u00a0  \u00a0 \u00a0 \u00a0 Begin\r\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Istr11;\r\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Istr12;\r\n\u00a0  \u00a0 \u00a0 \u00a0 End\r\n\u00a0  End\r\nElse\r\n\u00a0  Begin\r\n\u00a0 \u00a0 \u00a0 Istr21;\r\n\u00a0 \u00a0 \u00a0 Istr22;\r\n\u00a0  End;<\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Un programmatore <em>inesperto<\/em> potrebbe produrre, per il secondo diagramma di flusso, il codice seguente<\/p>\n<pre>If A > 0 Then\r\n \u00a0 If B > 0 Then\r\n\u00a0 \u00a0 \u00a0 Begin\r\n \u00a0 \u00a0 \u00a0 \u00a0 Istr11;\r\n \u00a0 \u00a0 \u00a0 \u00a0 Istr12;\r\n\u00a0 \u00a0 \u00a0 End\r\nElse             { ... ERRORE! ... }\r\n \u00a0 Begin\r\n\u00a0 \u00a0 \u00a0 Istr21;\r\n\u00a0 \u00a0 \u00a0 Istr22;\r\n \u00a0 End;<\/pre>\n<p>Purtroppo il compilatore lo interpreter\u00e0 come corrispondente al primo diagramma&#8230;<\/p>\n<ul>\n<li>il compilatore non prende in considerazione l&#8217;indentazione ma associa <em>correttamente<\/em> l&#8217;<strong>Else<\/strong> all&#8217;ultimo <strong>If<\/strong> rimasto <em>aperto<\/em><\/li>\n<li>il ramo <strong>Else<\/strong> si sposta da sinistra verso destra, <em>ciondola<\/em><\/li>\n<li>l&#8217;uso delle etichette di apertura e chiusura dei blocchi risolve l&#8217;ambiguit\u00e0.<\/li>\n<\/ul>\n<p>Il programmatore <em>alle prime armi<\/em> dovrebbe utilizzare <strong>sempre<\/strong> le etichette di inizio e fine blocco, anche nel caso di istruzioni singole, per evitare di incorrere nell&#8217;errore dell&#8217;<em>else ciondolante<\/em>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Considera attentamente\u00a0i due diagrammi di flusso e le\u00a0codifiche corrispondenti If A > 0 Then \u00a0 Begin \u00a0 \u00a0 \u00a0 If B > 0 Then \u00a0 \u00a0 \u00a0 \u00a0 Begin \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Istr11; \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Istr12; \u00a0 \u00a0 \u00a0 \u00a0 End \u00a0 \u00a0 Else \u00a0 \u00a0 \u00a0 \u00a0 &#8230; <a title=\"Alternativa ciondolante\" class=\"read-more\" href=\"https:\/\/www.valcon.it\/pascal\/alternativa-ciondolante\/\" aria-label=\"Leggi di pi\u00f9 su Alternativa ciondolante\">Leggi tutto<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"_links":{"self":[{"href":"https:\/\/www.valcon.it\/pascal\/wp-json\/wp\/v2\/posts\/351"}],"collection":[{"href":"https:\/\/www.valcon.it\/pascal\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.valcon.it\/pascal\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.valcon.it\/pascal\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.valcon.it\/pascal\/wp-json\/wp\/v2\/comments?post=351"}],"version-history":[{"count":6,"href":"https:\/\/www.valcon.it\/pascal\/wp-json\/wp\/v2\/posts\/351\/revisions"}],"predecessor-version":[{"id":357,"href":"https:\/\/www.valcon.it\/pascal\/wp-json\/wp\/v2\/posts\/351\/revisions\/357"}],"wp:attachment":[{"href":"https:\/\/www.valcon.it\/pascal\/wp-json\/wp\/v2\/media?parent=351"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.valcon.it\/pascal\/wp-json\/wp\/v2\/categories?post=351"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.valcon.it\/pascal\/wp-json\/wp\/v2\/tags?post=351"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}