csdn_文档中心_c++中的内部连接与外部连接(二).htm
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lang=EN-US>inline</SPAN></B><B><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">类成员函数定义总有外部连接，不论这个成员函数是静态、虚拟还是一般成员函数，类静态数据成员定义总有外部连接。</SPAN><SPAN
lang=EN-US><o:p></o:p></SPAN></B></FONT> </P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=3><SPAN
lang=EN-US><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes"> </SPAN><SPAN
style="mso-tab-count: 1"> </SPAN>1.</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">类的定义有内部连接。如果不是，想象一下你在</SPAN><SPAN
lang=EN-US>4</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">个</SPAN><SPAN
lang=EN-US>cpp</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">文件中</SPAN><SPAN
lang=EN-US>include</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">定义了类</SPAN><SPAN
lang=EN-US>Base</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的头文件，在</SPAN><SPAN
lang=EN-US>4</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">个编译单元中的类</SPAN><SPAN
lang=EN-US>Base</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">都有外部连接，在连接的时候就会出错。</SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=3><SPAN
lang=EN-US><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes"> </SPAN><SPAN
style="mso-tab-count: 1"> </SPAN></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">看下面的例子</SPAN><SPAN
lang=EN-US>:</SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN
lang=EN-US><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN><SPAN
style="COLOR: green">//main.cpp<o:p></o:p></SPAN></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=3><SPAN
lang=EN-US style="COLOR: green"><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN>class B<SPAN
style="mso-tab-count: 3">
</SPAN><SPAN
style="mso-tab-count: 2">
</SPAN>//</SPAN><SPAN
style="COLOR: green; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">类定义，内部连接</SPAN><SPAN
lang=EN-US style="COLOR: green"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN>{<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=3><SPAN
lang=EN-US style="COLOR: green"><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN><SPAN style="mso-tab-count: 1">
</SPAN>static int s_i;<SPAN
style="mso-tab-count: 3">
</SPAN>//</SPAN><SPAN
style="COLOR: green; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">静态类成员声明，内部连接</SPAN><SPAN
lang=EN-US style="COLOR: green"><SPAN
style="mso-tab-count: 2">
</SPAN><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN>public:<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=3><SPAN
lang=EN-US style="COLOR: green"><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN><SPAN
style="mso-tab-count: 1">
</SPAN>void foo() { ++s_i;}<SPAN style="mso-tab-count: 1">
</SPAN>//</SPAN><SPAN
style="COLOR: green; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">类</SPAN><SPAN
lang=EN-US style="COLOR: green">inline</SPAN><SPAN
style="COLOR: green; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">函数，内部连接</SPAN><SPAN
lang=EN-US style="COLOR: green"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN>};<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN>struct D <o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN>{<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=3><SPAN
lang=EN-US style="COLOR: green"><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN><SPAN
style="mso-tab-count: 1">
</SPAN>void foo();<SPAN
style="mso-tab-count: 3">
</SPAN>//</SPAN><SPAN
style="COLOR: green; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">类成员函数声明，内部连接</SPAN><SPAN
lang=EN-US style="COLOR: green"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN>};<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=3><SPAN
lang=EN-US style="COLOR: green"><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes"> </SPAN>int
B::s_i = 0;<SPAN
style="mso-tab-count: 1">
</SPAN><SPAN
style="mso-tab-count: 3">
</SPAN>//</SPAN><SPAN
style="COLOR: green; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">类静态数据成员定义，外部连接</SPAN><SPAN
lang=EN-US style="COLOR: green"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=3><SPAN
lang=EN-US style="COLOR: green"><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN>void D::foo() <SPAN
style="mso-tab-count: 2">
</SPAN><SPAN
style="mso-tab-count: 2">
</SPAN>//</SPAN><SPAN
style="COLOR: green; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">类成员函数定义，外部连接</SPAN><SPAN
lang=EN-US style="COLOR: green"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes"> </SPAN>{
<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN><SPAN
style="mso-tab-count: 1">
</SPAN>cout << "D::foo in main.cpp"
<<endl;<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN>}<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=3><SPAN
lang=EN-US style="COLOR: green"><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes"> </SPAN>int
main()<SPAN
style="mso-tab-count: 2">
</SPAN><SPAN
style="mso-tab-count: 2">
</SPAN><SPAN
style="mso-tab-count: 1">
</SPAN>//main</SPAN><SPAN
style="COLOR: green; FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">函数，全局自由函数，外部连接</SPAN><SPAN
lang=EN-US style="COLOR: green"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN>{<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN
style="mso-spacerun: yes"> </SPAN>B
b;<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN
style="mso-spacerun: yes"> </SPAN>D
d;<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN
style="mso-spacerun: yes">
</SPAN>return 0;<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN>}<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN><o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN>//a.cpp<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN>class B<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN><SPAN style="mso-spacerun: yes">
</SPAN>{<o:p></o:p></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US
style="COLOR: green"><FONT size=3><SPAN
style="mso-tab-count: 1">
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