不完全读取页面的时候能看到代码，

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<div>&nbsp;品(466291086)&nbsp;11:08:35&nbsp;<br /><span style="font-family: mceinline;"><strong>&nbsp;a=4；(a++)&nbsp;+=&nbsp;a&nbsp;&nbsp;&nbsp;&nbsp;；&nbsp;&nbsp;求a</strong></span><br />(本消息由该成员通过手机QQ发送，体验手机QQ请登录：&nbsp;http://mobile.qq.com/c&nbsp;)&nbsp;&nbsp;<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:09:13&nbsp;<br />9<br />【提示：此用户正在使用WebQQ：http://web.qq.com/】&nbsp;<br />秦伟(871452271)&nbsp;11:09:14&nbsp;<br />9？<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:09:22&nbsp;<br />呵呵&nbsp;<br />品(466291086)&nbsp;11:09:28&nbsp;<br />额饿&nbsp;&nbsp;<br />品(466291086)&nbsp;11:09:35&nbsp;<br />高手&nbsp;&nbsp;<br />cuiwow(157808076)&nbsp;11:09:40&nbsp;<br />这个不是要看具体编译器么..？<br />品(466291086)&nbsp;11:09:44&nbsp;<br />再来个&nbsp;&nbsp;<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:09:47&nbsp;<br />？&nbsp;<br />品(466291086)&nbsp;11:09:52&nbsp;<br /><img src="file:///D:/temp/S-1-5-~1/temp/PV(SCAJM1FB~YMS%2L}R5JU.gif" alt="" />&nbsp;&nbsp;<br />lander(530468003)&nbsp;11:09:51&nbsp;<br />搞这么复杂<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:10:04&nbsp;<br />群里是不是好几天没人说话了&nbsp;<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:10:05&nbsp;<br />哈哈&nbsp;<br />踏雪无痕(348259989)&nbsp;11:10:23&nbsp;<br />我也觉的得看编译器<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:10:27&nbsp;<br />放5.1群里也都放假了&nbsp;<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:10:32&nbsp;<br />为什么&nbsp;<br />品(466291086)&nbsp;11:10:37&nbsp;<br />&nbsp;(++a)&nbsp;+=&nbsp;(a++);<br />a&nbsp;=&nbsp;?&nbsp;&nbsp;<br />品(466291086)&nbsp;11:10:49&nbsp;<br /><img src="file:///D:/temp/S-1-5-~1/temp/AV5W2LR]H5YAQXT}1N2LPDY.gif" alt="" />&nbsp;&nbsp;<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:11:03&nbsp;<br />阴险，哈哈&nbsp;<br />品(466291086)&nbsp;11:11:06&nbsp;<br />哈哈哈&nbsp;&nbsp;<br />品(466291086)&nbsp;11:11:21&nbsp;<br />&nbsp;(++a)&nbsp;+=&nbsp;(a++);<br />a&nbsp;=&nbsp;?&nbsp;&nbsp;<br />醉里笑紅尘□(464469131)&nbsp;11:11:59&nbsp;<br />刚才你的那个题结果怎么是9啊&nbsp;？？<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:12:00&nbsp;<br />10&nbsp;<br />醉里笑紅尘□(464469131)&nbsp;11:12:09&nbsp;<br />怎么算的？？<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:12:09&nbsp;<br />？&nbsp;<br />醉里笑紅尘□(464469131)&nbsp;11:12:13&nbsp;<br />可否赐教？？<br />品(466291086)&nbsp;11:12:30&nbsp;<br />4+4+1&nbsp;&nbsp;<br />醉里笑紅尘□(464469131)&nbsp;11:12:46&nbsp;<br />能具体点吗？？<br />品(466291086)&nbsp;11:13:07&nbsp;<br />这个答案&nbsp;(++a)&nbsp;+=&nbsp;(a++);<br />a&nbsp;=&nbsp;?多少啊&nbsp;&nbsp;<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:13:09&nbsp;<br />从右向左求值&nbsp;<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:13:26&nbsp;<br />10？&nbsp;<br />品(466291086)&nbsp;11:13:29&nbsp;<br />我用的手机&nbsp;&nbsp;哥哥&nbsp;&nbsp;<br />品(466291086)&nbsp;11:13:33&nbsp;<br />哈哈哈&nbsp;&nbsp;<br />品(466291086)&nbsp;11:13:36&nbsp;<br /><img src="file:///D:/temp/S-1-5-~1/temp/AV5W2LR]H5YAQXT}1N2LPDY.gif" alt="" />&nbsp;&nbsp;<br />醉里笑紅尘□(464469131)&nbsp;11:13:55&nbsp;<br />但是我实在不懂啊！<br />品(466291086)&nbsp;11:13:57&nbsp;<br />先看看对不&nbsp;&nbsp;&nbsp;这个题&nbsp;&nbsp;<br />品(466291086)&nbsp;11:14:06&nbsp;<br /><img src="file:///D:/temp/S-1-5-~1/temp/AV5W2LR]H5YAQXT}1N2LPDY.gif" alt="" />&nbsp;&nbsp;<br />lander(530468003)&nbsp;11:14:22&nbsp;<br />好无聊啊<br />品(466291086)&nbsp;11:14:33&nbsp;<br />等我下课&nbsp;&nbsp;&nbsp;单m&nbsp;&nbsp;<br />品(466291086)&nbsp;11:14:51&nbsp;<br />呃呃<img src="file:///D:/temp/S-1-5-~1/temp/]F{S%KHON132NOE`VB([Z[2.gif" alt="" />&nbsp;&nbsp;<br />品(466291086)&nbsp;11:15:37&nbsp;<br />下了&nbsp;&nbsp;&nbsp;看老师无聊<img src="file:///D:/temp/S-1-5-~1/temp/52W[C~~FFQ[27)18U93ZOWB.gif" alt="" />&nbsp;&nbsp;<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:16:02&nbsp;<br />上当了&nbsp;<br />品(466291086)&nbsp;11:16:19&nbsp;<br />呵呵&nbsp;&nbsp;<br />cuiwow(157808076)&nbsp;11:16:55&nbsp;<br />表达式可以当左值么？<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:17:15&nbsp;<br />a++&nbsp;返回是有值&nbsp;<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:17:21&nbsp;<br />悲剧&nbsp;<br />cuiwow(157808076)&nbsp;11:17:38&nbsp;<br />呃&nbsp;是么<br />品(466291086)&nbsp;11:17:42&nbsp;<br /><img src="file:///D:/temp/S-1-5-~1/temp/S)YLEQANPE}LG]K8ZBSL6IU.gif" alt="" />&nbsp;&nbsp;<br />品(466291086)&nbsp;11:18:01&nbsp;<br />还是这牛&nbsp;&nbsp;<br />品(466291086)&nbsp;11:18:14&nbsp;<br />怎么可以呢&nbsp;&nbsp;<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:21:25&nbsp;<br />++a返回的也不是左值？&nbsp;<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:21:42&nbsp;<br />？？？&nbsp;<br />cuiwow(157808076)&nbsp;11:21:55&nbsp;<br />表达式不都是右值么<br />ITGrit[C/C++&nbsp;MFC](286715286)&nbsp;11:22:18&nbsp;<br />哦？那我搞错了&nbsp;<br />醉里笑紅尘□(464469131)&nbsp;11:23:21&nbsp;<br />右值左传！</div>

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<div><strong>那么什么是左值和右值呢</strong></div>

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<p>&nbsp; &nbsp;通俗的讲，左值就是能够出现在赋值符号左面的东西，而右值就是那些可以出现在赋值符号右面的东西了。</p>

<p>举个很简单的例子：</p>

<p>a=b+100;</p>

<p>那么这里a就是左值，b+25就是一个右值。左值和右值之间是不一定都能互换的，上面的这个例子就是不能互换的，如果写成</p>

<p>b＋100＝a;</p>

<p>大家都能看出来这样写会不编译通过的，因为编译器无法判断b+100的内存地址，所以不能操作。</p>

<p>看了这个例子，可以做一个总结，左值必须应该是一个变量或者是表达式等，但是它的物理位置是可以确定的，而右值不一定,这也是它们两者之间的区别。</p>

<p>关于左值是表达式的例子有数组，还有指针这些都可以。</p>

<p>int array[10];</p>

<p>int a=5;</p>

<p>array[a+3]=10; //这里左值就是一个数组表达式了</p>

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<p>另外：<a id="AjaxHolder_Comments_CommentList_ctl03_NameLink" target="_blank">liotta</a>朋友给了一些其他方面的提示 （左值右值翻译可能有些问题）</p>

<div><strong>错了，没有什么左值和右值！<br />翻译害人不浅，</strong><br />L-value中的L指的是Location，表示可寻址。The "l" in lvalue can be though of as location<br />R-value中的R指的是Read，表示可读。The "r" in rvalue can be thought of as "read" value. &nbsp;&nbsp;</div>

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