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📁 C++程序编写规范,适合C++中级读者
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<div class=Section1 style='layout-grid:15.6pt'>

<h3><span lang=EN-US>30. </span><span style='font-family:宋体;mso-ascii-font-family:
Arial;mso-hansi-font-family:Arial'>避免重载</span><span lang=EN-US>&amp;&amp;, ||, </span><span
style='font-family:宋体;mso-ascii-font-family:Arial;mso-hansi-font-family:Arial'>或</span><span
lang=EN-US>, </span><span style='font-family:宋体;mso-ascii-font-family:Arial;
mso-hansi-font-family:Arial'>（逗号）。</span></h3>

<p class=MsoNormal><span lang=EN-US><o:p>&nbsp;</o:p></span></p>

<p class=MsoNormal><b style='mso-bidi-font-weight:normal'><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>摘要</span><span lang=EN-US><o:p></o:p></span></b></p>

<p class=MsoNormal><span lang=EN-US><o:p>&nbsp;</o:p></span></p>

<p class=MsoNormal><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>明智意味着知道何时应该有所节制：内建的</span><b
style='mso-bidi-font-weight:normal'><span lang=EN-US>&amp;&amp;</span></b><span
lang=EN-US>, <b style='mso-bidi-font-weight:normal'>||</b> , </span><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>和</span><b style='mso-bidi-font-weight:normal'><span
lang=EN-US>,</span></b><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>（逗号）享受编译器的特殊待遇。如果重载这些操作符，它们就变成了普通的函数，具有完全不同的语义（这会违反第</span><span
lang=EN-US>26</span><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>和第</span><span lang=EN-US>31</span><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>条），这还是一种引入难以察觉的错虫和脆弱性的有效途径。不要幼稚地重载这些操作符。</span></p>

<p class=MsoNormal><span lang=EN-US><o:p>&nbsp;</o:p></span></p>

<p class=MsoNormal><b style='mso-bidi-font-weight:normal'><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>讨论</span><span lang=EN-US><o:p></o:p></span></b></p>

<p class=MsoNormal><span lang=EN-US><o:p>&nbsp;</o:p></span></p>

<p class=MsoNormal><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>不要重载</span><b style='mso-bidi-font-weight:
normal'><span lang=EN-US>operator&amp;&amp;</span></b><span lang=EN-US>, <b
style='mso-bidi-font-weight:normal'>operator||</b> , </span><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>或</span><b style='mso-bidi-font-weight:normal'><span
lang=EN-US>operator,</span></b><span style='font-family:宋体;mso-ascii-font-family:
"Times New Roman";mso-hansi-font-family:"Times New Roman"'>（逗号）的主要原因在于你无法实现这三种内建操作符的完整语义，而程序员一般都认为它们具有这样的语义。尤其是，内建的版本是从左到右求值的，</span><b
style='mso-bidi-font-weight:normal'><span lang=EN-US>&amp;&amp;</span></b><span
style='font-family:宋体;mso-ascii-font-family:"Times New Roman";mso-hansi-font-family:
"Times New Roman"'>和</span><b style='mso-bidi-font-weight:normal'><span
lang=EN-US>||</span></b><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>还使用短路求值法（</span><span lang=EN-US>short-circuit
evaluation</span><span style='font-family:宋体;mso-ascii-font-family:"Times New Roman";
mso-hansi-font-family:"Times New Roman"'>）。</span></p>
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