https://forge.codesys.com/forge/talk/Deutsch/thread/8d227c2221/2020-02-28T01:04:56.737000ZRecent posts to POINTER vs REFERENCE2020-02-28T01:04:56.737000Z2020-02-28T01:04:56.737000Zguerillerohttps://forge.codesys.com/u/guerillero/https://forge.codesys.comda42652aba8c62243e11f3650c42193a09e4deaf

<div class="markdown_content"><p>REFERENCE benötigt genau so viel Speicher wie ein POINTER? 32Bit?</p> <div class="codehilite"><pre><span></span><span class="nl">Beispiel</span><span class="p">:</span><span class="w"></span> <span class="nl">Deklaration</span><span class="p">:</span><span class="w"></span> <span class="n">ivar</span><span class="w"> </span><span class="err">:</span><span class="w"> </span><span class="nc">INT</span><span class="p">;</span><span class="w"> </span> <span class="n">ref_int</span><span class="w"> </span><span class="err">:</span><span class="w"> </span><span class="n">REFERENCE</span><span class="w"> </span><span class="k">TO</span><span class="w"> </span><span class="nc">INT</span><span class="p">;</span><span class="w"> </span> <span class="nl">ref_int0</span><span class="p">:</span><span class="w"> </span><span class="n">REFERENCE</span><span class="w"> </span><span class="k">TO</span><span class="w"> </span><span class="nc">INT</span><span class="p">;</span><span class="w"> </span> <span class="nl">testref</span><span class="p">:</span><span class="w"> </span><span class="n">BOOL</span><span class="w"> </span><span class="err">:</span><span class="o">=</span><span class="w"> </span><span class="k">FALSE</span><span class="p">;</span><span class="w"> </span> <span class="nl">Implementierung</span><span class="p">:</span><span class="w"></span> <span class="n">ivar</span><span class="w"> </span><span class="err">:</span><span class="o">=</span><span class="w"> </span><span class="n">ivar</span><span class="w"> </span><span class="o">+</span><span class="mi">1</span><span class="p">;</span><span class="w"> </span> <span class="n">ref_int</span><span class="w"> </span><span class="k">REF</span><span class="o">=</span><span class="w"> </span><span class="o">[</span><span class="n">b</span><span class="o">]</span><span class="n">hugo</span><span class="o">[</span><span class="n">/b</span><span class="o">]</span><span class="p">;</span><span class="w">  </span><span class="o">&lt;</span><span class="c1">-- soll hier hugo stehen?</span> <span class="n">ref_int0</span><span class="w"> </span><span class="k">REF</span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"> </span> <span class="n">testref</span><span class="w"> </span><span class="err">:</span><span class="o">=</span><span class="w"> </span><span class="n">__ISVALIDREF</span><span class="p">(</span><span class="n">ref_int</span><span class="p">);</span><span class="w">  </span><span class="p">(</span><span class="o">*</span><span class="w"> </span><span class="n">wird</span><span class="w"> </span><span class="k">TRUE</span><span class="p">,</span><span class="w"> </span><span class="n">weil</span><span class="w"> </span><span class="n">ref_int</span><span class="w"> </span><span class="n">auf</span><span class="w"> </span><span class="n">ivar</span><span class="w"> </span><span class="n">zeigt</span><span class="p">,</span><span class="w"> </span><span class="n">das</span><span class="w"> </span><span class="n">einen</span><span class="w"> </span><span class="n">Wert</span><span class="w"> </span><span class="n">ungleich</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="n">hat</span><span class="w"> </span><span class="o">*</span><span class="p">)</span><span class="w"> </span> <span class="n">testref0</span><span class="w"> </span><span class="err">:</span><span class="o">=</span><span class="w"> </span><span class="n">__ISVALIDREF</span><span class="p">(</span><span class="n">ref_int0</span><span class="p">);</span><span class="w">   </span><span class="p">(</span><span class="o">*</span><span class="w"> </span><span class="n">wird</span><span class="w"> </span><span class="k">FALSE</span><span class="p">,</span><span class="w"> </span><span class="n">weil</span><span class="w"> </span><span class="n">ref_int</span><span class="w"> </span><span class="n">auf</span><span class="w"> </span><span class="mi">0</span><span class="w"> </span><span class="n">gesetzt</span><span class="w"> </span><span class="n">ist</span><span class="w"> </span><span class="o">*</span><span class="p">)</span><span class="w"> </span> </pre></div> </div>

2020-02-28T01:04:54.920000Z2020-02-28T01:04:54.920000Zguerillerohttps://forge.codesys.com/u/guerillero/https://forge.codesys.com9821f1558b90ab5b86fa35993713e172dfac8d1c

<div class="markdown_content"><p>Ok, und es gibt anscheinend keine Möglichlkeit die Adresse an der der Wert steht an eine andere Referenz zu übergeben.</p></div>

2020-02-28T01:04:53.029000Z2020-02-28T01:04:53.029000Zguerillerohttps://forge.codesys.com/u/guerillero/https://forge.codesys.comb3fc95e9766595089f32600c1f3d2af1dc0b1475

<div class="markdown_content"><p>Hi,</p> <p>Danke, d.h. immer wenn ich keine wilden "intertypischen" operationen vor habe sollte ich besser eine Referez nutzen?</p> <p>Gruß</p> <p>Michael</p></div>

2020-02-28T01:04:48.050000Z2020-02-28T01:04:48.050000Zsingletonhttps://forge.codesys.com/u/singleton/https://forge.codesys.com9b8b979b896805b997032a1252c38e1098cda87b

<div class="markdown_content"><p>Hi,<br/> eine Referenz ist typsicher. Wenn Du also einen ganz bestimmten Typ erwartest, kannst Du das mit einem Pointer nicht sicherstellen, mit einer Referenz schon.</p></div>

2020-02-28T01:04:46.275000Z2020-02-28T01:04:46.275000Zguerillerohttps://forge.codesys.com/u/guerillero/https://forge.codesys.com1bdb26185575b47cebae817168381a9d68ace5d8

<div class="markdown_content"><p>Hallo,</p> <p>kann mir jemand den unterschied zwischen Pointer und Referece erläutern. Zwar habe ich die Hilfe und die Suche bemüht jedoch erschließt sich mir der Unterschied nicht wirklich.</p> <p>Kann jemand ein einfaches Beispiel nennen, wann man besser einen Pointer und wann man eine besser Reference nutzt?</p> <p>Gruß</p> <p>Michael</p></div>