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从www.CppReference.com打包的C++参考手册

  string&amp; replace( <strong>size_type</strong> index1, <strong>size_type</strong> num1, const string&amp; str, <strong>size_type</strong> index2, <strong>size_type</strong> num2 );
  string&amp; replace( <strong>size_type</strong> index, <strong>size_type</strong> num, const char* str );
  string&amp; replace( <strong>size_type</strong> index, <strong>size_type</strong> num1, const char* str, <strong>size_type</strong> num2 );
  string&amp; replace( <strong>size_type</strong> index, <strong>size_type</strong> num1, <strong>size_type</strong> num2, char ch );
  string&amp; replace( iterator start, iterator end, const string&amp; str );
  string&amp; replace( iterator start, iterator end, const char* str );
  string&amp; replace( iterator start, iterator end, const char* str, <strong>size_type</strong> num );
  string&amp; replace( iterator start, iterator end, <strong>size_type</strong> num, char ch );
</pre>

  <p>The function replace() either:</p>

  <ul>
    <li>replaces characters of the current string with up to
    <em>num</em> characters from <em>str</em>, beginning at
    <em>index</em>,</li>

    <li>replaces up to <em>num1</em> characters of the current string
    (starting at <em>index1</em>) with up to <em>num2</em> characters
    from <em>str</em> beginning at <em>index2</em>,</li>

    <li>replaces up to <em>num</em> characters of the current string
    with characters from <em>str</em>, beginning at <em>index</em> in
    <em>str</em>,</li>

    <li>replaces up to <em>num1</em> characters in the current string
    (beginning at <em>index1</em>) with <em>num2</em> characters from
    <em>str</em> beginning at <em>index2</em>,</li>

    <li>replaces up to <em>num1</em> characters in the current string
    (beginning at <em>index</em>) with <em>num2</em> copies of
    <em>ch</em>,</li>

    <li>replaces the characters in the current string from
    <em>start</em> to <em>end</em> with <em>str</em>,</li>

    <li>replaces characters in the current string from <em>start</em>
    to <em>end</em> with <em>num</em> characters from
    <em>str</em>,</li>

    <li>or replaces the characters in the current string from
    <em>start</em> to <em>end</em> with <em>num</em> copies of
    <em>ch</em>.</li>
  </ul>

  <p>For example, the following code displays the string &quot;They say
  he carved it himself...find your soul-mate, Homer.&quot;</p>
  <pre class="example-code">
   string s = &quot;They say he carved it himself...from a BIGGER spoon&quot;;
   string s2 = &quot;find your soul-mate, Homer.&quot;;
   s.replace( 32, s2.length(), s2 );
   cout &lt;&lt; s &lt;&lt; endl;               
</pre>

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

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

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

  <div class="syntax-name-format">
    Syntax:
  </div>
  <pre class="syntax-box">
  #include &lt;string&gt;
  void reserve( <strong>size_type</strong> size );
</pre>

  <p>The reserve() function sets the capacity of the string to at least
  <em>size</em>.</p>

  <p>reserve() runs in <a href="../complexity.html">linear
  time</a>.</p>

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

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

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

  <div class="syntax-name-format">
    Syntax:
  </div>
  <pre class="syntax-box">
  #include &lt;string&gt;
  void resize( <strong>size_type</strong> size, const <a href=
"../containers.html">TYPE</a>&amp; val = <a href=
"../containers.html">TYPE</a>() );
</pre>

  <p>The function resize() changes the size of the string to
  <em>size</em>. If <em>val</em> is specified then any newly-created
  elements will be initialized to have a value of <em>val</em>.</p>

  <p>This function runs in <a href="../complexity.html">linear
  time</a>.</p>

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

  <div class="related-content">
    (C++ Multimaps) <a href=
    "../cppmultimap/multimap_constructors.html">Multimap constructors
    &amp; destructors</a><br>
    <a href="capacity.html">capacity</a><br>
    <a href="size.html">size</a>
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<hr>

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

  <div class="syntax-name-format">
    Syntax:
  </div>
  <pre class="syntax-box">
  #include &lt;string&gt;
  <strong>size_type</strong> rfind( const string&amp; str, <strong>size_type</strong> index );
  <strong>size_type</strong> rfind( const char* str, <strong>size_type</strong> index );
  <strong>size_type</strong> rfind( const char* str, <strong>size_type</strong> index, <strong>size_type</strong> num );
  <strong>size_type</strong> rfind( char ch, <strong>size_type</strong> index );
</pre>

  <p>The rfind() function either:</p>

  <ul>
    <li>returns the location of the first occurrence of <em>str</em> in
    the current string, doing a reverse search from <em>index</em>,
    string::npos if nothing is found,</li>

    <li>returns the location of the first occurrence of <em>str</em> in
    the current string, doing a reverse search from <em>index</em>,
    searching at most <em>num</em> characters, string::npos if nothing
    is found,</li>

    <li>or returns the location of the first occurrence of <em>ch</em>
    in the current string, doing a reverse search from <em>index</em>,
    string::npos if nothing is found.</li>
  </ul>

  <p>For example, in the following code, the first call to rfind()
  returns string::npos, because the target word is not within the first
  8 characters of the string. However, the second call returns 9,
  because the target word is within 20 characters of the beginning of
  the string.</p>
  <pre class="example-code">
   int loc;
   string s = &quot;My cat&#39;s breath smells like cat food.&quot;;
   loc = s.rfind( &quot;breath&quot;, 8 );
   cout &lt;&lt; &quot;The word breath is at index &quot; &lt;&lt; loc &lt;&lt; endl;
   loc = s.rfind( &quot;breath&quot;, 20 );
   cout &lt;&lt; &quot;The word breath is at index &quot; &lt;&lt; loc &lt;&lt; endl;           
</pre>

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

  <div class="related-content">
    <a href="find.html">find</a><br>
    <a href="find_first_not_of.html">find_first_not_of</a><br>
    <a href="find_first_of.html">find_first_of</a><br>
    <a href="find_last_not_of.html">find_last_not_of</a><br>
    <a href="find_last_of.html">find_last_of</a>
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<hr>

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

  <div class="syntax-name-format">
    Syntax:
  </div>
  <pre class="syntax-box">
  #include &lt;string&gt;
  <strong>size_type</strong> size() const;
</pre>

  <p>The size() function returns the number of elements in the current
  string.</p>

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

  <div class="related-content">
    <a href="capacity.html">capacity</a><br>
    <a href="empty.html">empty</a><br>
    <a href="length.html">length</a><br>
    <a href="max_size.html">max_size</a><br>
    <a href="resize.html">resize</a>
  </div>
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<hr>

  <div class="name-format">
    String constructors
  </div>

  <div class="syntax-name-format">
    Syntax:
  </div>
  <pre class="syntax-box">
  #include &lt;string&gt;
  string();
  string( const string&amp; s );
  string( <strong>size_type</strong> length, const char&amp; ch );
  string( const char* str );
  string( const char* str, <strong>size_type</strong> length );
  string( const string&amp; str, <strong>size_type</strong> index, <strong>size_type</strong> length );
  string( <a href=
"../iterators.html">input_iterator</a> start, <a href="../iterators.html">input_iterator</a> end );
  ~string();
</pre>

  <p>The string constructors create a new string containing:</p>

  <ul>
    <li>nothing; an empty string,</li>

    <li>a copy of the given string <em>s</em>,</li>

    <li><em>length</em> copies of <em>ch</em>,</li>

    <li>a duplicate of <em>str</em> (optionally up to <em>length</em>
    characters long),</li>

    <li>a substring of <em>str</em> starting at <em>index</em> and
    <em>length</em> characters long</li>

    <li>a string of characterss denoted by the <em>start</em> and
    <em>end</em> iterators</li>
  </ul>

  <p>For example,</p>
  <pre class="example-code">
   string str1( 5, &#39;c&#39; );
   string str2( &quot;Now is the time...&quot; );
   string str3( str2, 11, 4 );
   cout &lt;&lt; str1 &lt;&lt; endl;
   cout &lt;&lt; str2 &lt;&lt; endl;
   cout &lt;&lt; str3 &lt;&lt; endl;            
</pre>

  <p>displays</p>
  <pre class="example-code">
   ccccc
   Now is the time...
   time         
</pre>

  <p>The string constructors usually run in <a href=
  "../complexity.html">linear time</a>, except the empty constructor,
  which runs in <a href="../complexity.html">constant time</a>.</p>
  </div>
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<hr>

  <div class="name-format">
    String operators
  </div>

  <div class="syntax-name-format">
    Syntax:
  </div>
  <pre class="syntax-box">
  #include &lt;string&gt;
  bool operator==(const string&amp; c1, const string&amp; c2);
  bool operator!=(const string&amp; c1, const string&amp; c2);
  bool operator&lt;(const string&amp; c1, const string&amp; c2);
  bool operator&gt;(const string&amp; c1, const string&amp; c2);
  bool operator&lt;=(const string&amp; c1, const string&amp; c2);
  bool operator&gt;=(const string&amp; c1, const string&amp; c2);
  string operator+(const string&amp; s1, const string&amp; s2 );
  string operator+(const char* s, const string&amp; s2 );
  string operator+( char c, const string&amp; s2 );
  string operator+( const string&amp; s1, const char* s );
  string operator+( const string&amp; s1, char c );
  ostream&amp; operator&lt;&lt;( ostream&amp; os, const string&amp; s );
  istream&amp; operator&gt;&gt;( istream&amp; is, string&amp; s );
  string&amp; operator=( const string&amp; s );
  string&amp; operator=( const char* s );
  string&amp; operator=( char ch );
  char&amp; operator[]( <strong>size_type</strong> index );
</pre>

  <p>C++ strings can be compared and assigned with the standard
  comparison operators: ==, !=, &lt;=, &gt;=, &lt;, &gt;, and =.
  Performing a comparison or assigning one string to another takes
  <a href="../complexity.html">linear time</a>.</p>

  <p>Two strings are equal if:</p>
  <pre class="example-code">
  1. Their size is the same, and
  2. Each member in location i in one string is equal to the the member in location i in the other string.              
</pre>

  <p>Comparisons among strings are done lexicographically.</p>

  <p>In addition to these normal (C++ Multimaps) <a href=
  "../cppmultimap/multimap_operators.html">Multimap operators</a>,
  strings can also be concatenated with the + operator and fed to the
  C++ I/O stream classes with the &lt;&lt; and &gt;&gt; operators.</p>

  <p>For example, the following code concatenates two strings and
  displays the result:</p>
  <pre class="example-code">
 string s1 = &quot;Now is the time...&quot;;
 string s2 = &quot;for all good men...&quot;;
 string s3 = s1 + s2;
 cout &lt;&lt; &quot;s3 is &quot; &lt;&lt; s3 &lt;&lt; endl;            
</pre>

  <p>Futhermore, strings can be assigned values that are other
  strings, character arrays, or even single characters. The following
  code is perfectly valid:</p>
  <pre class="example-code">
 char ch = &#39;N&#39;;
 string s;
 s = ch;         
</pre>

  <p>Individual characters of a string can be examined with the []
  operator, which runs in <a href="../complexity.html">constant
  time</a>.</p>

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

  <div class="related-content">
    (C++ Multimaps) <a href=
    "../cppmultimap/multimap_operators.html">Multimap
    operators</a><br>
    <a href="c_str.html">c_str</a><br>
    <a href="compare.html">compare</a><br>
    <a href="data.html">data</a>
  </div>
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<hr>

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

  <div class="syntax-name-format">
    Syntax:
  </div>
  <pre class="syntax-box">
  #include &lt;string&gt;
  string substr( <strong>size_type</strong> index, <strong>size_type</strong> num = npos );
</pre>

  <p>The substr() function returns a substring of the current string,
  starting at <em>index</em>, and <em>num</em> characters long. If
  <em>num</em> is omitted, it will default to string::npos, and the
  substr() function will simply return the remainder of the string
  starting at <em>index</em>.</p>

  <p>For example:</p>
  <pre class="example-code">
   string s(&quot;What we have here is a failure to communicate&quot;);
   string sub = s.substr(21);
   cout &lt;&lt; &quot;The original string is &quot; &lt;&lt; s &lt;&lt; endl;
   cout &lt;&lt; &quot;The substring is &quot; &lt;&lt; sub &lt;&lt; endl;              
</pre>

  <p>displays</p>
  <pre class="example-code">
   The original string is What we have here is a failure to communicate
   The substring is a failure to communicate            
</pre>

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

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

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

  <div class="syntax-name-format">
    Syntax:
  </div>
  <pre class="syntax-box">
  #include &lt;string&gt;
  void swap( container&amp; from );
</pre>

  <p>The swap() function exchanges the elements of the current string
  with those of <em>from</em>. This function operates in <a href=
  "../complexity.html">constant time</a>.</p>

  <p>For example, the following code uses the swap() function to
  exchange the values of two strings:</p>
  <pre class="example-code">
   string first( &quot;This comes first&quot; );
   string second( &quot;And this is second&quot; );
   first.swap( second );
   cout &lt;&lt; first &lt;&lt; endl;
   cout &lt;&lt; second &lt;&lt; endl;          
</pre>

  <p>The above code displays:</p>
  <pre class="example-code">
   And this is second
   This comes first             
</pre>

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

  <div class="related-content">
    (C++ Lists) <a href="../cpplist/splice.html">splice</a>
  </div>
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<hr>
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