📄 lex_3806.htm

📁 ARM编辑、编译软件
💻 HTM
字号:
<HTML><TITLE>lexicographical_compare</TITLE><BODY>
<A HREF="ref.htm"><IMG SRC="images/banner.gif"></A>
<P><STRONG>Click on the banner to return to the Class Reference home page.</STRONG></P>
<P>&copy;Copyright 1996 Rogue Wave Software</P>
<H2>lexicographical_compare</H2>
<HR><PRE>     Algorithm</PRE><HR>
<A NAME="Summary"><H3>Summary</H3></A>
<P>Compares two ranges lexicographically.</P>
<H3>Contents</H3>
<UL>
<A HREF="#Synopsis"><LI>Synopsis</LI></A>
<A HREF="#Description"><LI>Description</LI></A>
<A HREF="#Complexity"><LI>Complexity</LI></A>
<A HREF="#Example"><LI>Example</LI></A>
<A HREF="#Warning"><LI>Warning</LI></A>
</UL>
<A NAME="Synopsis"><H3>Synopsis</H3></A>
<PRE>#include &#60;algorithm></PRE>
<PRE>
template &#60;class InputIterator1, class InputIterator2>
 bool
 <B>lexicographical_compare</B>(InputIterator1 first,
                         InputIterator2 last1,
                         InputIterator2 first2,
                         InputIterator last2);
template &#60;class InputIterator1, class InputIterator2, class Compare>
 bool
 <B>lexicographical_compare</B>(InputIterator1 first,
                         InputIterator2 last1,
                         InputIterator2 first2,
                         InputIterator last2, Compare comp);</PRE>
<A NAME="Description"><H3>Description</H3></A>
<P>The <B><I>lexicographical_compare</B></I> functions compare each element in the range <SAMP>[first1, last1)</SAMP> to the corresponding element in the range <SAMP>[first2, last2)</SAMP> using iterators <SAMP>i</SAMP> and <SAMP>j</SAMP>.  </P>
<P>The first version of the algorithm uses <SAMP>operator&#60;</SAMP> as the default comparison operator.  It immediately returns <SAMP>true</SAMP> if it encounters any pair in which <SAMP>*i</SAMP> is less than <SAMP>*j</SAMP>, and immediately returns <SAMP>false</SAMP> if <SAMP>*j</SAMP> is less than <SAMP>*i</SAMP>.  If the algorithm reaches the end of the first sequence before reaching the end of the second sequence, it also returns <SAMP>true</SAMP>. </P>
<P>The second version of the function takes an argument <SAMP>comp</SAMP> that defines a comparison function that is used in place of the default <SAMP>operator&#60;.</SAMP></P>
<P>The <B><I>lexicographical_compare</B></I> functions can be used with all the datatypes provided by the standard library.</P>
<A NAME="Complexity"><H3>Complexity</H3></A>
<P><B><I>lexicographical_compare</B></I> performs at most <SAMP>min((last1 - first1), (last2  -  first2))</SAMP> applications of the comparison function.</P>
<A NAME="Example"><H3>Example</H3></A>
<PRE>//
// lex_comp.cpp
//
 #include &#60;algorithm>
 #include &#60;vector>
 #include &#60;iostream.h>
 
 int main(void)
 { 
   int d1[5] = {1,3,5,32,64}; 
   int d2[5] = {1,3,2,43,56};
  
   // set up vector  
   vector&#60;int> v1(d1,d1 + 5), v2(d2,d2 + 5);      
 
   // Is v1 less than v2 (I think not)
   bool b1 =  <B>lexicographical_compare</B>(v1.begin(), 
              v1.end(), v2.begin(), v2.end());
   // Is v2 less than v1 (yup, sure is)
   bool b2 =  <B>lexicographical_compare</B>(v2.begin(), 
            v2.end(), v1.begin(), v1.end(), less&#60;int>());
   cout &#60;&#60; (b1 ? "TRUE" : "FALSE") &#60;&#60; " " 
        &#60;&#60; (b2 ? "TRUE" : "FALSE") &#60;&#60; endl;
   return 0;
 }
Output:
 FALSE TRUE
</PRE>
<A NAME="Warning"><H3>Warning</H3></A>
<P>If your compiler does not support default template parameters, then you need to always supply the <SAMP>Allocator</SAMP> template argument.  For instance, you'll have to write :</P>
<P><SAMP>vector&#60;int, allocator></SAMP></P>
<P>instead of :</P>
<P><SAMP>vector&#60;int></SAMP></P>
<HR>
<A HREF="les_5595.htm"><IMG SRC="images/prev.gif"></A> <A HREF="ref.htm#contents"><IMG SRC="images/toc.gif"></A> <A HREF="lim_2532.htm"><IMG SRC="images/next.gif"></A></BODY></HTML>
⌨️ 快捷键说明

复制代码 Ctrl + C
搜索代码 Ctrl + F
全屏模式 F11
切换主题 Ctrl + Shift + D
显示快捷键 ?
增大字号 Ctrl + =
减小字号 Ctrl + -