subject_58166.htm

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序号：58166 发表者：陈昕 发表日期：2003-10-30 14:33:20
<br>主题：各位大侠，请教一个很菜的问题
<br>内容：我不知道在c++下怎么产生随机数，我找了三本书，也看了msdn。但还是找不到，我对类完全不了解。（大二学生，才学过c）问老师，那些动口不动手的白痴也讲不清，所以来请教大家了，请告诉我一个算法，和必须include的文件。
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<font color=red>答案被接受</font><br>回复者：ohye212 回复日期：2003-10-30 14:50:19
<br>内容：#include &lt;stdlib.h&gt;<BR>#include &lt;stdio.h&gt;<BR>#include &lt;time.h&gt;<BR><BR>void main( void )<BR>{<BR>&nbsp;&nbsp; int i;<BR><BR>&nbsp;&nbsp; /* Seed the random-number generator with current time so that<BR>&nbsp;&nbsp;&nbsp;&nbsp;* the numbers will be different every time we run.<BR>&nbsp;&nbsp;&nbsp;&nbsp;*/<BR>&nbsp;&nbsp; srand( (unsigned)time( NULL ) );<BR><BR>&nbsp;&nbsp; /* Display 10 numbers. */<BR>&nbsp;&nbsp; for( i = 0;&nbsp;&nbsp; i &lt; 10;i++ )<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;printf( &#34;&nbsp;&nbsp;%6d\n&#34;, rand() );<BR>}<BR>
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回复者：michael 回复日期：2003-10-30 14:51:30
<br>内容：int rand( void );<BR><BR>Routine Required Header Compatibility <BR>rand &lt;stdlib.h&gt; ANSI, Win 95, Win NT <BR><BR><BR>For additional compatibility information, see Compatibility in the Introduction.<BR><BR>Libraries<BR><BR>LIBC.LIB Single thread static library, retail version <BR>LIBCMT.LIB Multithread static library, retail version <BR>MSVCRT.LIB Import library for MSVCRT.DLL, retail version <BR><BR><BR>Return Value<BR><BR>rand returns a pseudorandom number, as described above. There is no error return.<BR><BR>Remarks<BR><BR>The rand function returns a pseudorandom integer in the range 0 to RAND_MAX. Use the srand function to seed the pseudorandom-number generator before calling rand.<BR><BR>Example<BR><BR>/* RAND.C: This program seeds the random-number generator<BR> * with the time, then displays 10 random integers.<BR> */<BR><BR>#include &lt;stdlib.h&gt;<BR>#include &lt;stdio.h&gt;<BR>#include &lt;time.h&gt;<BR><BR>void main( void )<BR>{<BR>&nbsp;&nbsp; int i;<BR><BR>&nbsp;&nbsp; /* Seed the random-number generator with current time so that<BR>&nbsp;&nbsp;&nbsp;&nbsp;* the numbers will be different every time we run.<BR>&nbsp;&nbsp;&nbsp;&nbsp;*/<BR>&nbsp;&nbsp; srand( (unsigned)time( NULL ) );<BR><BR>&nbsp;&nbsp; /* Display 10 numbers. */<BR>&nbsp;&nbsp; for( i = 0;&nbsp;&nbsp; i &lt; 10;i++ )<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;printf( &#34;&nbsp;&nbsp;%6d\n&#34;, rand() );<BR>}<BR><BR><BR>Output<BR><BR>&nbsp;&nbsp;&nbsp;&nbsp;6929<BR>&nbsp;&nbsp;&nbsp;&nbsp;8026<BR>&nbsp;&nbsp; 21987<BR>&nbsp;&nbsp; 30734<BR>&nbsp;&nbsp; 20587<BR>&nbsp;&nbsp;&nbsp;&nbsp;6699<BR>&nbsp;&nbsp; 22034<BR>&nbsp;&nbsp; 25051<BR>&nbsp;&nbsp;&nbsp;&nbsp;7988<BR>&nbsp;&nbsp; 10104<BR>摘自《MSDN》
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回复者：陈昕 回复日期：2003-10-30 19:42:56
<br>内容：能具体告诉我生成0－52之间的随机数的算法，或是你的算法生成数的最大值吗？小弟谢谢了。
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回复者：汪永明 回复日期：2003-10-30 20:08:30
<br>内容：你把srand()和rand()生成的随机数拿来对53取余啊。就有0-52的数了。
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回复者：陈昕 回复日期：2003-10-31 08:52:02
<br>内容：谢谢各位的指导，不过小弟我的问题没完全解决。你们给的方法只能在一个很短的时间内生成一个随机数，但我要把随机数生成在一个这样的程序里：<BR>srand( (unsigned)time( NULL ) );<BR>for(i=1;i&lt;100000;i++)<BR>{b=rand();<BR> ...............<BR> ..............<BR>}<BR>在这么短的执行过程中，我的系统只给我生成了4，5个随机数，不过我在MSDN的资料中看到过Random类，那会有帮助吗，但我的MSDN没有它的使用例子，谁能帮帮我啊？<BR>&nbsp;&nbsp; 
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