跟crackman读SAS程序（91）--宏程序中表达式里面的数值比较

shiyiming

From crackman's blog on Baidu


               
                <p>%macro aa;<br>
%let condition=( 1.2&gt;=1 and 1.2&lt;1.5 ) and ( 1123&gt;=800 and 1123&lt;1200 );</p>
<p>%if &amp;condition %then %do;<br>
&nbsp;&nbsp;&nbsp;  %put x;<br>
&nbsp;&nbsp;  %end;<br>
&nbsp;&nbsp;  %else %do;<br>
%put M;<br>
&nbsp;&nbsp;  %end;<br>
&nbsp;&nbsp;  %mend aa;<br>
%aa;</p>
<p>这个结果是X</p>
<p>%macro aa;<br>
%let condition=( 1.2&gt;=1 and 1.2&lt;1.5 ) and ( 1123.1&gt;=800 and 1123.1&lt;1200 );</p>
<p>%if &amp;condition %then %do;<br>
&nbsp;&nbsp;&nbsp;  %put x;<br>
&nbsp;&nbsp;  %end;<br>
&nbsp;&nbsp;  %else %do;<br>
%put M;<br>
&nbsp;&nbsp;  %end;<br>
&nbsp;&nbsp;  %mend aa;<br>
%aa;</p>
<p>结果是M</p>
<p>解释是这样的：</p>
<p> %macro aa;<br>
&nbsp;&nbsp;  %put ERROR-%nrstr(%eval(1999999999.9 &gt; 9) --&gt;) <strong><font color="#ff0000">%eval</font></strong>(199999999.1&gt;9);<br>
&nbsp;&nbsp;  %put ERROR-%nrstr(%sysevalf(1999999999.9 &gt; 9) --&gt;) <strong><font color="#ff0000">%sysevalf</font></strong>(199999999.1&gt;9);<br>
%mend aa;<br>
%aa<br>
宏编译器在解析这个语句的时候，是要区别数据类型，也是类型不同的数据比较，返回为FALSE，也就是0。</p>
<p>谢谢hopewell。</p> <a href="http://hi.baidu.com/crack%5Fman/blog/item/40222e7bccccf80729388a88.html">阅读全文</a>
               
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