📄 [c++对象模型][3]指针与数组 - itech's blog - 博客园.htm
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style="COLOR: #000000">;<BR> </SPAN><SPAN
style="COLOR: #0000ff">double</SPAN><SPAN
style="COLOR: #000000"> arr2[] </SPAN><SPAN
style="COLOR: #000000">=</SPAN><SPAN style="COLOR: #000000"> {</SPAN><SPAN
style="COLOR: #800080">1.0</SPAN><SPAN style="COLOR: #000000">,</SPAN><SPAN
style="COLOR: #800080">2.0</SPAN><SPAN style="COLOR: #000000">,</SPAN><SPAN
style="COLOR: #800080">3.0</SPAN><SPAN
style="COLOR: #000000">};<BR> </SPAN><SPAN
style="COLOR: #008000">//</SPAN><SPAN
style="COLOR: #008000">double arr3[3] = arr; </SPAN><SPAN
style="COLOR: #008000">//</SPAN><SPAN
style="COLOR: #008000"> error</SPAN><SPAN
style="COLOR: #008000"><BR></SPAN><SPAN
style="COLOR: #000000"> PrintArray(arr,</SPAN><SPAN
style="COLOR: #800080">3</SPAN><SPAN
style="COLOR: #000000">);<BR> PrintArray(</SPAN><SPAN
style="COLOR: #000000">&</SPAN><SPAN style="COLOR: #000000">arr[</SPAN><SPAN
style="COLOR: #800080">0</SPAN><SPAN style="COLOR: #000000">],</SPAN><SPAN
style="COLOR: #800080">3</SPAN><SPAN
style="COLOR: #000000">);<BR> PrintArray(arr2);<BR><BR> </SPAN><SPAN
style="COLOR: #0000ff">double</SPAN><SPAN
style="COLOR: #000000"> matrix2 [</SPAN><SPAN
style="COLOR: #800080">2</SPAN><SPAN style="COLOR: #000000">][</SPAN><SPAN
style="COLOR: #800080">2</SPAN><SPAN style="COLOR: #000000">] </SPAN><SPAN
style="COLOR: #000000">=</SPAN><SPAN style="COLOR: #000000"> {</SPAN><SPAN
style="COLOR: #800080">1.0</SPAN><SPAN style="COLOR: #000000">,</SPAN><SPAN
style="COLOR: #800080">0.0</SPAN><SPAN style="COLOR: #000000">,</SPAN><SPAN
style="COLOR: #800080">0.0</SPAN><SPAN style="COLOR: #000000">,</SPAN><SPAN
style="COLOR: #800080">1.0</SPAN><SPAN
style="COLOR: #000000">};<BR> </SPAN><SPAN
style="COLOR: #0000ff">double</SPAN><SPAN
style="COLOR: #000000"> matrix3 [</SPAN><SPAN
style="COLOR: #800080">3</SPAN><SPAN style="COLOR: #000000">][</SPAN><SPAN
style="COLOR: #800080">3</SPAN><SPAN style="COLOR: #000000">] </SPAN><SPAN
style="COLOR: #000000">=</SPAN><SPAN style="COLOR: #000000"> {{</SPAN><SPAN
style="COLOR: #800080">1.0</SPAN><SPAN style="COLOR: #000000">,</SPAN><SPAN
style="COLOR: #800080">0.0</SPAN><SPAN style="COLOR: #000000">,</SPAN><SPAN
style="COLOR: #800080">0.0</SPAN><SPAN
style="COLOR: #000000">},<BR> {</SPAN><SPAN
style="COLOR: #800080">0.0</SPAN><SPAN style="COLOR: #000000">,</SPAN><SPAN
style="COLOR: #800080">1.0</SPAN><SPAN style="COLOR: #000000">,</SPAN><SPAN
style="COLOR: #800080">0.0</SPAN><SPAN
style="COLOR: #000000">},<BR> {</SPAN><SPAN
style="COLOR: #800080">0.0</SPAN><SPAN style="COLOR: #000000">,</SPAN><SPAN
style="COLOR: #800080">0.0</SPAN><SPAN style="COLOR: #000000">,</SPAN><SPAN
style="COLOR: #800080">1.0</SPAN><SPAN
style="COLOR: #000000">}};<BR> PrintArray(matrix3[</SPAN><SPAN
style="COLOR: #800080">0</SPAN><SPAN style="COLOR: #000000">],</SPAN><SPAN
style="COLOR: #800080">3</SPAN><SPAN style="COLOR: #000000">*</SPAN><SPAN
style="COLOR: #800080">3</SPAN><SPAN
style="COLOR: #000000">);<BR> PrintArray(</SPAN><SPAN
style="COLOR: #000000">&</SPAN><SPAN
style="COLOR: #000000">matrix3[</SPAN><SPAN style="COLOR: #800080">0</SPAN><SPAN
style="COLOR: #000000">][</SPAN><SPAN style="COLOR: #800080">0</SPAN><SPAN
style="COLOR: #000000">],</SPAN><SPAN style="COLOR: #800080">3</SPAN><SPAN
style="COLOR: #000000">*</SPAN><SPAN style="COLOR: #800080">3</SPAN><SPAN
style="COLOR: #000000">);<BR> </SPAN><SPAN
style="COLOR: #008000">//</SPAN><SPAN
style="COLOR: #008000">PrintArray(matrix3,3*3);</SPAN><SPAN
style="COLOR: #008000"><BR></SPAN><SPAN
style="COLOR: #000000"> PrintArray(matrix3);<BR><BR> </SPAN><SPAN
style="COLOR: #008000">//</SPAN><SPAN
style="COLOR: #008000"> 指针来模拟数组</SPAN><SPAN
style="COLOR: #008000"><BR></SPAN><SPAN
style="COLOR: #000000"> </SPAN><SPAN
style="COLOR: #0000ff">double</SPAN><SPAN
style="COLOR: #000000"> </SPAN><SPAN style="COLOR: #000000">*</SPAN><SPAN
style="COLOR: #000000">p3 </SPAN><SPAN style="COLOR: #000000">=</SPAN><SPAN
style="COLOR: #000000"> </SPAN><SPAN style="COLOR: #0000ff">new</SPAN><SPAN
style="COLOR: #000000"> </SPAN><SPAN
style="COLOR: #0000ff">double</SPAN><SPAN
style="COLOR: #000000">[GetLength()];<BR> p3[</SPAN><SPAN
style="COLOR: #800080">0</SPAN><SPAN style="COLOR: #000000">] </SPAN><SPAN
style="COLOR: #000000">=</SPAN><SPAN style="COLOR: #000000"> </SPAN><SPAN
style="COLOR: #800080">10.0</SPAN><SPAN
style="COLOR: #000000">;<BR> p3[</SPAN><SPAN
style="COLOR: #800080">1</SPAN><SPAN style="COLOR: #000000">] </SPAN><SPAN
style="COLOR: #000000">=</SPAN><SPAN style="COLOR: #000000"> </SPAN><SPAN
style="COLOR: #800080">20.0</SPAN><SPAN
style="COLOR: #000000">;<BR> p3[</SPAN><SPAN
style="COLOR: #800080">2</SPAN><SPAN style="COLOR: #000000">] </SPAN><SPAN
style="COLOR: #000000">=</SPAN><SPAN style="COLOR: #000000"> </SPAN><SPAN
style="COLOR: #800080">30.0</SPAN><SPAN
style="COLOR: #000000">;<BR> PrintArray(p3,</SPAN><SPAN
style="COLOR: #800080">3</SPAN><SPAN
style="COLOR: #000000">);<BR> PrintArray(p3);<BR> delete []p3;<BR><BR> </SPAN><SPAN
style="COLOR: #008000">//</SPAN><SPAN
style="COLOR: #008000"> 数组+指针实现二维变长数组</SPAN><SPAN
style="COLOR: #008000"><BR></SPAN><SPAN
style="COLOR: #000000"> </SPAN><SPAN
style="COLOR: #0000ff">double</SPAN><SPAN
style="COLOR: #000000"> </SPAN><SPAN style="COLOR: #000000">*</SPAN><SPAN
style="COLOR: #000000">p4[</SPAN><SPAN style="COLOR: #800080">2</SPAN><SPAN
style="COLOR: #000000">];<BR> p4[</SPAN><SPAN
style="COLOR: #800080">0</SPAN><SPAN style="COLOR: #000000">] </SPAN><SPAN
style="COLOR: #000000">=</SPAN><SPAN style="COLOR: #000000"> </SPAN><SPAN
style="COLOR: #0000ff">new</SPAN><SPAN style="COLOR: #000000"> </SPAN><SPAN
style="COLOR: #0000ff">double</SPAN><SPAN style="COLOR: #000000">[</SPAN><SPAN
style="COLOR: #800080">2</SPAN><SPAN
style="COLOR: #000000">];<BR> p4[</SPAN><SPAN
style="COLOR: #800080">1</SPAN><SPAN style="COLOR: #000000">] </SPAN><SPAN
style="COLOR: #000000">=</SPAN><SPAN style="COLOR: #000000"> </SPAN><SPAN
style="COLOR: #0000ff">new</SPAN><SPAN style="COLOR: #000000"> </SPAN><SPAN
style="COLOR: #0000ff">double</SPAN><SPAN style="COLOR: #000000">[</SPAN><SPAN
style="COLOR: #800080">4</SPAN><SPAN
style="COLOR: #000000">];<BR> p4[</SPAN><SPAN
style="COLOR: #800080">0</SPAN><SPAN style="COLOR: #000000">][</SPAN><SPAN
style="COLOR: #800080">0</SPAN><SPAN style="COLOR: #000000">] </SPAN><SPAN
style="COLOR: #000000">=</SPAN><SPAN style="COLOR: #000000"> </SPAN><SPAN
style="COLOR: #800080">10</SPAN><SPAN
style="COLOR: #000000">;<BR> p4[</SPAN><SPAN
style="COLOR: #800080">0</SPAN><SPAN style="COLOR: #000000">][</SPAN><SPAN
style="COLOR: #800080">1</SPAN><SPAN style="COLOR: #000000">] </SPAN><SPAN
style="COLOR: #000000">=</SPAN><SPAN style="COLOR: #000000"> </SPAN><SPAN
style="COLOR: #800080">20</SPAN><SPAN
style="COLOR: #000000">;<BR> p4[</SPAN><SPAN
style="COLOR: #800080">1</SPAN><SPAN style="COLOR: #000000">][</SPAN><SPAN
style="COLOR: #800080">0</SPAN><SPAN style="COLOR: #000000">] </SPAN><SPAN
style="COLOR: #000000">=</SPAN><SPAN style="COLOR: #000000"> </SPAN><SPAN
style="COLOR: #800080">30</SPAN><SPAN
style="COLOR: #000000">;<BR> p4[</SPAN><SPAN
style="COLOR: #800080">1</SPAN><SPAN style="COLOR: #000000">][</SPAN><SPAN
style="COLOR: #800080">1</SPAN><SPAN style="COLOR: #000000">] </SPAN><SPAN
style="COLOR: #000000">=</SPAN><SPAN style="COLOR: #000000"> </SPAN><SPAN
style="COLOR: #800080">40</SPAN><SPAN
style="COLOR: #000000">;<BR> p4[</SPAN><SPAN
style="COLOR: #800080">1</SPAN><SPAN style="COLOR: #000000">][</SPAN><SPAN
style="COLOR: #800080">2</SPAN><SPAN style="COLOR: #000000">] </SPAN><SPAN
style="COLOR: #000000">=</SPAN><SPAN style="COLOR: #000000"> </SPAN><SPAN
style="COLOR: #800080">50</SPAN><SPAN
style="COLOR: #000000">;<BR> p4[</SPAN><SPAN
style="COLOR: #800080">1</SPAN><SPAN style="COLOR: #000000">][</SPAN><SPAN
style="COLOR: #800080">3</SPAN><SPAN style="COLOR: #000000">] </SPAN><SPAN
style="COLOR: #000000">=</SPAN><SPAN style="COLOR: #000000"> </SPAN><SPAN
style="COLOR: #800080">60</SPAN><SPAN
style="COLOR: #000000">;<BR> PrintArray(p4[</SPAN><SPAN
style="COLOR: #800080">0</SPAN><SPAN style="COLOR: #000000">],</SPAN><SPAN
style="COLOR: #800080">2</SPAN><SPAN
style="COLOR: #000000">);<BR> PrintArray(p4[</SPAN><SPAN
style="COLOR: #800080">1</SPAN><SPAN style="COLOR: #000000">],</SPAN><SPAN
style="COLOR: #800080">4</SPAN><SPAN
style="COLOR: #000000">);<BR> delete [] p4[</SPAN><SPAN
style="COLOR: #800080">0</SPAN><SPAN
style="COLOR: #000000">];<BR> delete [] p4[</SPAN><SPAN
style="COLOR: #800080">1</SPAN><SPAN
style="COLOR: #000000">];<BR><BR> PrintArray(arr); </SPAN><SPAN
style="COLOR: #008000">//</SPAN><SPAN
style="COLOR: #008000"> 数组传参为传指针，所以函数内可以修改</SPAN><SPAN
style="COLOR: #008000"><BR></SPAN><SPAN
style="COLOR: #000000"> ChangeArray(arr);<BR> PrintArray(arr);<BR>}</SPAN></SPAN></DIV>
<P> </P>
<P>代码分析总结：</P>
<P><SPAN style="COLOR: #ff0000">1）数组的定义必须使用常量指定长度，例如：double
arr[3]，但是使用指针时可以是运行时指定，例如double *p3 = new
double[getLength()]。<BR>2）数组定义时即分配空间且在栈上，不需要程序员来对内存管理，但是如果对指针使用了new[]，则必须由程序员在使用完毕后delete[]。<BR>3)
一维数组数组名即第一个元素的地址，例如：double arr[3]中，arr ==
&arr[0]为true。<BR>4）二维数组中第一行的地址即为第一个元素的地址，例如：double matrix3 [3][3]，matrix[0]
== &matrix[0][0]为true。<BR>5）可以使用指针数组来模拟变长二维数组，例如：double *p4[2]; p4[0] = new
double[2]; p4[1] = new
double[4];<BR>6）二维数组内存中同一维数组仍为连续的区域，所以可以将二维数组和一维相互转化。<BR>7）一维数组名即为第一个元素的地址，所以可以同指针隐式转化，但二维数组名不是第一个元素地址，所以不能转化。<BR>8)
当函数传入数组，实际传首元素的指针，所以可以在函数内修改数组元素。<BR></SPAN></P>
<P>三 完！</P>
<DIV id=MySignature>
<P>感谢，Thanks！<BR><BR>作者：<A href="http://itech.cnblogs.com/">iTech</A><BR>出处：<A
href="http://itech.cnblogs.com/">http://itech.cnblogs.com/</A>
<BR>转载：本文版权归作者iTech所有，转载请注明出处，不得用于商业用途！</P></DIV>
<DIV id=EntryTag>Tag标签: <A
href="http://www.cnblogs.com/itech/tag/[Cpp对象模å]/">[Cpp对象模型]</A></DIV></DIV>
<DIV class=postDesc>posted @ 2009-02-22 13:57 <A
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