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学习MAkefile相关的好资料

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        <span id="ArticleTitle1_ArticleTitle1_lblTitle">跟我一起写 Makefile（十）</span></b>&nbsp;&nbsp;&nbsp;&nbsp;
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      <span id="ArticleTitle1_ArticleTitle1_lblKeywords">C C++ make makefile</span></td>
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                <td><span id="ArticleContent1_ArticleContent1_lblContent"><P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p></SPAN></P>
<H3 style="MARGIN: 13pt 0cm"><FONT size=2><SPAN style="FONT-FAMILY: 'Courier New'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">四、</SPAN><SPAN lang=EN-US>foreach </SPAN><SPAN style="FONT-FAMILY: 'Courier New'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">函数</SPAN></FONT></H3>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">foreach</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>函数和别的函数非常的不一样。因为这个函数是用来做循环用的，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">Makefile</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>中的</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">foreach</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>函数几乎是仿照于</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">Unix</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>标准</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">Shell</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>（</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">/bin/sh</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>）中的</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">for</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>语句，或是</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">C-Shell</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>（</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">/bin/csh</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>）中的</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">foreach</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">语句而构建的。它的语法是：</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-tab-count: 1">&nbsp;&nbsp;&nbsp; </SPAN>$(foreach &lt;var&gt;,&lt;list&gt;,&lt;text&gt;)<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>这个函数的意思是，把参数</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;list&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>中的单词逐一取出放到参数</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;var&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>所指定的变量中，然后再执行</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;text&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>所包含的表达式。每一次</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;text&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>会返回一个字符串，循环过程中，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;text&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>的所返回的每个字符串会以空格分隔，最后当整个循环结束时，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;text&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>所返回的每个字符串所组成的整个字符串（以空格分隔）将会是</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">foreach</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">函数的返回值。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>所以，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;var&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>最好是一个变量名，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;list&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>可以是一个表达式，而</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;text&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>中一般会使用</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;var&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>这个参数来依次枚举</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;list&gt;</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">中的单词。举个例子：</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>names := a b c d<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>files := $(foreach n,$(names),$(n).o)<o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>上面的例子中，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">$(name)</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>中的单词会被挨个取出，并存到变量“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">n</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>”中，“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">$(n).o</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>”每次根据“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">$(n)</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>”计算出一个值，这些值以空格分隔，最后作为</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">foreach</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>函数的返回，所以，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">$(files)</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>的值是“</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">a.o b.o c.o d.o</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">”。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>注意，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">foreach</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>中的</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;var&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>参数是一个临时的局部变量，</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">foreach</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>函数执行完后，参数</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">&lt;var&gt;</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>的变量将不在作用，其作用域只在</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">foreach</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">函数当中。</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<H3 style="MARGIN: 13pt 0cm"><FONT size=2><SPAN style="FONT-FAMILY: 'Courier New'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">五、</SPAN><SPAN lang=EN-US>if </SPAN><SPAN style="FONT-FAMILY: 'Courier New'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman'; mso-ascii-font-family: 'Times New Roman'">函数</SPAN></FONT></H3>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">if</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>函数很像</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">GNU</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>的</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">make</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>所支持的条件语句——</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">ifeq</SPAN><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'"><FONT face=宋体>（参见前面所述的章节），</FONT></SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'">if</SPAN><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">函数的语法是：</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><SPAN style="mso-spacerun: yes">&nbsp;&nbsp;&nbsp; </SPAN>$(if &lt;condition&gt;,&lt;then-part&gt;) <o:p></o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><FONT face=宋体><SPAN style="FONT-SIZE: 9pt; mso-ascii-font-family: 'Courier New'">或是</SPAN><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p></o:p></SPAN></FONT></P>
<P class=MsoPlainText style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US style="FONT-SIZE: 9pt; FONT-FAMILY: 'Courier New'"><o:p>&nbsp;</o:p></SPAN></P>