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从www.CppReference.com打包的C++参考手册

    }

    int var;
    double var2;
  };

  ...

  Base* b = new ("Base instance 1") Base;
</pre>

  <p>If an int is 4 bytes and a double is 8 bytes, the above code
  generates the following output when run:</p>

  <pre class="example-code">
  Logging an allocation of 12 bytes for new object 'Base instance 1'
</pre>

  <div class="related-name-format">
    Related topics:
  </div>

  <div class="related-content">
    <a href="delete.html">delete</a><br>
    (Standard C Memory) <a href="../stdmem/free.html">free</a><br>
    (Standard C Memory) <a href="../stdmem/malloc.html">malloc</a>
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<hr>

  <div class="name-format">
    operator
  </div>

  <div class="syntax-name-format">
    Syntax:
  </div>
  <pre class="syntax-box">
  return-type class-name::operator#(parameter-list) {
  ...
  }
  return-type operator#(parameter-list) {
  ...
  }
</pre>

  <p>The operator keyword is used to overload operators. The sharp sign
  (#) listed above in the syntax description represents the operator
  which will be overloaded. If part of a class, the <em>class-name</em>
  should be specified. For unary operators, <em>parameter-list</em>
  should be empty, and for binary operators, <em>parameter-list</em>
  should contain the operand on the right side of the operator (the
  operand on the left side is passed as <a href=
  "this.html">this</a>).</p>

  <p>For the non-member operator overload function, the operand on the
  left side should be passed as the first parameter and the operand on
  the right side should be passed as the second parameter.</p>

  <p>You cannot overload the #, ##, ., :, .*, or ? tokens.</p>

  <div class="related-name-format">
    Related topics:
  </div>

  <div class="related-content">
    <a href="this.html">this</a>
  </div>
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<hr>

  <div class="name-format">
    private
  </div>

  <p>Private data of a class can only be accessed by members of that
  class, except when <a href="friend.html">friend</a> is used. The
  <a href="private.html">private</a> keyword can also be used to
  inherit a base class privately, which causes all <a href=
  "public.html">public</a> and <a href="protected.html">protected</a>
  members of the base class to become private members of the derived
  class.</p>

  <div class="related-name-format">
    Related topics:
  </div>

  <div class="related-content">
    <a href="class.html">class</a><br>
    <a href="protected.html">protected</a><br>
    <a href="public.html">public</a>
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<hr>

  <div class="name-format">
    protected
  </div>

  <p>Protected data are private to their own class but can be inherited
  by derived classes. The protected keyword can also be used as an
  inheritance specifier, which causes all <a href=
  "public.html">public</a> and protected members of the base class to
  become protected members of the derived class.</p>

  <div class="related-name-format">
    Related topics:
  </div>

  <div class="related-content">
    <a href="class.html">class</a><br>
    <a href="private.html">private</a><br>
    <a href="public.html">public</a>
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<hr>

  <div class="name-format">
    public
  </div>

  <p>Public data in a class are accessible to everyone. The public
  keyword can also be used as an inheritance specifier, which causes
  all public and <a href="protected.html">protected</a> members of the
  base class to become public and protected members of the derived
  class.</p>

  <div class="related-name-format">
    Related topics:
  </div>

  <div class="related-content">
    <a href="class.html">class</a><br>
    <a href="private.html">private</a><br>
    <a href="protected.html">protected</a>
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<hr>

  <div class="name-format">
    register
  </div>

  <p>The register keyword requests that a variable be optimized for
  speed, and fell out of common use when computers became better at
  most code optimizations than humans.</p>

  <div class="related-name-format">
    Related topics:
  </div>

  <div class="related-content">
    <a href="auto.html">auto</a>
  </div>
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<hr>

  <div class="name-format">
    reinterpret_cast
  </div>

  <div class="syntax-name-format">
    Syntax:
  </div>
  <pre class="syntax-box">
  reinterpret_cast&lt;type&gt; (object);
</pre>

  <p>The reinterpret_cast operator changes one data type into another.
  It should be used to cast between incompatible pointer types.</p>

  <div class="related-name-format">
    Related topics:
  </div>

  <div class="related-content">
    <a href="const_cast.html">const_cast</a><br>
    <a href="dynamic_cast.html">dynamic_cast</a><br>
    <a href="static_cast.html">static_cast</a>
  </div>
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<hr>

  <div class="name-format">
    return
  </div>

  <div class="syntax-name-format">
    Syntax:
  </div>
  <pre class="syntax-box">
  return;
  return( value );
</pre>

  <p>The return statement causes execution to jump from the current
  function to whatever function called the current function. An
  optional <em>value</em> can be returned. A function may have more
  than one return statement.</p>
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<hr>

  <div class="name-format">
    short
  </div>

  <p>The short keyword is a data type modifier that is used to declare
  short integer variables. See the <a href="../data_types.html">data
  types</a> page.</p>

  <div class="related-name-format">
    Related topics:
  </div>

  <div class="related-content">
    <a href="bool.html">bool</a><br>
    <a href="char.html">char</a><br>
    <a href="double.html">double</a><br>
    <a href="float.html">float</a><br>
    <a href="int.html">int</a><br>
    <a href="long.html">long</a><br>
    <a href="signed.html">signed</a><br>
    <a href="unsigned.html">unsigned</a><br>
    <a href="void.html">void</a><br>
    <a href="wchar_t.html">wchar_t</a>
  </div>
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  </table>
</body></html>
<hr>

  <div class="name-format">
    signed
  </div>

  <p>The signed keyword is a data type modifier that is usually used to
  declare signed char variables. See the <a href=
  "../data_types.html">data types</a> page.</p>

  <div class="related-name-format">
    Related topics:
  </div>

  <div class="related-content">
    <a href="bool.html">bool</a><br>
    <a href="char.html">char</a><br>
    <a href="double.html">double</a><br>
    <a href="float.html">float</a><br>
    <a href="int.html">int</a><br>
    <a href="long.html">long</a><br>
    <a href="short.html">short</a><br>
    <a href="unsigned.html">unsigned</a><br>
    <a href="void.html">void</a><br>
    <a href="wchar_t.html">wchar_t</a>
  </div>
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<hr>

  <div class="name-format">
    sizeof
  </div>

  <p>The sizeof operator is a compile-time operator that returns the
  size, in bytes, of the argument passed to it.  For example, the
  following code uses sizeof to display the sizes of a number of
  variables:</p>

  <pre class="example-code">
  struct EmployeeRecord {
    int ID;
    int age;
    double salary;
    EmployeeRecord* boss;
  };

  ...

  cout &lt;&lt; "sizeof(int): " &lt;&lt; sizeof(int) &lt;&lt; endl
       &lt;&lt; "sizeof(float): " &lt;&lt; sizeof(float) &lt;&lt; endl
       &lt;&lt; "sizeof(double): " &lt;&lt; sizeof(double) &lt;&lt; endl
       &lt;&lt; "sizeof(char): " &lt;&lt; sizeof(char) &lt;&lt; endl
       &lt;&lt; "sizeof(EmployeeRecord): " &lt;&lt; sizeof(EmployeeRecord) &lt;&lt; endl;

  int i;
  float f;
  double d;
  char c;
  EmployeeRecord er;

  cout &lt;&lt; "sizeof(i): " &lt;&lt; sizeof(i) &lt;&lt; endl
       &lt;&lt; "sizeof(f): " &lt;&lt; sizeof(f) &lt;&lt; endl
       &lt;&lt; "sizeof(d): " &lt;&lt; sizeof(d) &lt;&lt; endl
       &lt;&lt; "sizeof(c): " &lt;&lt; sizeof(c) &lt;&lt; endl
       &lt;&lt; "sizeof(er): " &lt;&lt; sizeof(er) &lt;&lt; endl;
</pre>

  <p>When run, the above code displays this output:</p>

  <pre class="example-code">
  sizeof(int): 4
  sizeof(float): 4
  sizeof(double): 8
  sizeof(char): 1
  sizeof(EmployeeRecord): 20
  sizeof(i): 4
  sizeof(f): 4
  sizeof(d): 8
  sizeof(c): 1
  sizeof(er): 20
</pre>

  <p>Note that sizeof can either take a variable type (such as
  <strong>int</strong>) or a variable name (such as <strong>i</strong>
  in the example above).</p>

  <p>It is also important to note that the sizes of various types of
  variables can change depending on what system you're on.  Check out
  <a href="../data_types.html">a description
  of the C and C++ data types</a> for more information.</p>

  <p>The parentheses around the argument are not required if you are
  using sizeof with a variable type (e.g. sizeof(int)).</p>

  <div class="related-name-format">
    Related topics:
  </div>

  <div class="related-content">
    <a href="../data_types.html">C/C++ Data Types</a>
  </div>

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<hr>

  <div class="name-format">
    static
  </div>

  <p>The static data type modifier is used to create permanent storage
  for variables. Static variables keep their value between function
  calls. When used in a <a href="class.html">class</a>, all
  instantiations of that class share one copy of the variable.</p>
  </div>
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  </table>
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<hr>

  <div class="name-format">
    static_cast
  </div>

  <div class="syntax-name-format">
    Syntax:
  </div>
  <pre class="syntax-box">
  static_cast&lt;type&gt; (object);
</pre>

  <p>The static_cast keyword can be used for any normal conversion
  between types. No runtime checks are performed.</p>

  <div class="related-name-format">
    Related topics:
  </div>

  <div class="related-content">
    <a href="const_cast.html">const_cast</a><br>
    <a href="dynamic_cast.html">dynamic_cast</a><br>
    <a href="reinterpret_cast.html">reinterpret_cast</a>
  </div>
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<hr>

  <div class="name-format">
    struct
  </div>

  <div class="syntax-name-format">
    Syntax:
  </div>
  <pre class="syntax-box">
  struct struct-name : inheritance-list {
  public-members-list;    
  protected:
  protected-members-list;
  private:
  private-members-list;
  } object-list;
</pre>

  <p>Structs are like `classes`, except that by default members of a
  struct are <a href="public.html">public</a> rather than <a href=
  "private.html">private</a>. In C, structs can only contain data and
  are not permitted to have inheritance lists. For example:</p>
  <pre class="example-code">
   struct Date {
     int Day;
     int Month;
     int Year;
   };           
</pre>

  <div class="related-name-format">
    Related topics:
  </div>

  <div class="related-content">
    <a href="class.html">class</a><br>
    <a href="union.html">union</a>
  </div>
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<hr>

  <div class="name-format">
    switch
  </div>

  <div class="syntax-name-format">
    Syntax:
  </div>
  <pre class="syntax-box">
  switch( expression ) {
  case A:
  statement list;
  break;
  case B:
  statement list;
  break;
  ...
  case N:
  statement list;
  break;
  default:
  statement list;
  break;
  }
</pre>

  <p>The switch statement allows you to test an expression for many
  values, and is commonly used as a replacement for multiple <a href=
  "if.html">if</a>()...<a href="else.html">else</a> <a href=
  "if.html">if</a>()...<a href="else.html">else</a> <a href=
  "if.html">if</a>()... statements. <a href="break.html">break</a>
  statements are required between each <a href="case.html">case</a>
  statement, otherwise execution will &quot;fall-through&quot; to the
  next <a href="case.html">case</a> statement. The <a href=
  "default.html">default</a> case is optional. If provided, it will
  match any case not explicitly covered by the preceding cases in the
  switch statement. For example:</p>
  <pre class="example-code">
   char keystroke = getch();
   switch( keystroke ) {
     case &#39;a&#39;:
     case &#39;b&#39;:
     case &#39;c&#39;:
     case &#39;d&#39;:
       KeyABCDPressed();
       break;
     case &#39;e&#39;:
       KeyEPressed();
       break;
     default:
       UnknownKeyPressed();
       break;
   }            
</pre>

  <div class="related-name-format">
    Related topics:
  </div>

  <div class="related-content">
    <a href="break.html">break</a><br>
    <a href="case.html">case</a><br>
    <a href="default.html">default</a><br>
    <a href="if.html">if</a>
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<hr>

  <div class="name-format">
    template
  </div>

  <div class="syntax-name-format">
    Syntax:
  </div>
  <pre class="syntax-box">
  template &lt;class data-type&gt; return-type name( parameter-list ) {
  statement-list;
  }
</pre>

  <p>Templates are used to create generic functions and can operate on
  data without knowing the nature of that data. They accomplish this by
  using a placeholder data-type for which many other <a href=
  "../data_types.html">data types</a> can be substituted.</p>

  <div class="related-examples-format">
    Example code:
  </div>

  <div class="related-examples">
    <p>For example, the following code uses a template to define a
    generic swap function that can swap two variables of any type:</p>