C/C++内存分配知识

末蓝、 2022-08-25 02:15 227阅读 0赞

原文出处：http://smilejay.com/2013/12/memory-allocation-in-c-and-cpp/

C语言中内存分为五个区:  
栈(stack)：用来存放函数的形参和函数内的局部变量。由编译器分配空间，在函数执行完后由编译器自动释放。  
堆(heap)：用来存放由动态分配函数（如malloc）分配的空间。是由程序员自己手动分配的，并且必须由程序员使用free释放。如果忘记用free释放，会导致所分配的空间一直占着不放，导致内存泄露。  
全局区/静态区：用来存放全局变量和静态变量。程序结束时由系统释放，分为全局初始化区和全局未初始化区；存在于程序的整个运行期间，是由编译器分配和释放的。  
文字常量区：常量字符串放于此，程序结束时由系统释放。例如char \*c = “123456”；则”123456”为文字常量，存放于文字常量区。也由编译器控制分配和释放。  
程序代码区：用来存放程序的二进制代码。

下面通过几个例子来看一下，具体C程序中的内存分配吧：

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 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(128,128,128)"&gt;&lt;em&gt;/*&nbsp;例1&nbsp;&nbsp;&nbsp;&nbsp;main1.c&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;*&nbsp;演示C程序中的内存分配方式。&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> */&lt;/em&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;#include&nbsp;&lt;stdlib.h&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;#include&nbsp;&lt;string.h&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(153,51,51)"&gt;int&lt;/span&gt;&nbsp;a&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;=&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,0,221)"&gt;0&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;;&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(102,102,102)"&gt;&lt;em&gt;//全局初始化区&lt;/em&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(153,51,51)"&gt;char&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;*&lt;/span&gt;p1&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;;&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(102,102,102)"&gt;&lt;em&gt;//全局未初始化区&lt;/em&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(153,51,51)"&gt;int&lt;/span&gt;&nbsp;main&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;(&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;)&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;{&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(153,51,51)"&gt;int&lt;/span&gt;&nbsp;b&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;;&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(102,102,102)"&gt;&lt;em&gt;//栈&lt;/em&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(153,51,51)"&gt;char&lt;/span&gt;&nbsp;s&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;[&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;]&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;=&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(255,0,0)"&gt;"abc"&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;;&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(102,102,102)"&gt;&lt;em&gt;//s在栈,"abc\0"在文字常量区&lt;/em&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(153,51,51)"&gt;char&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;*&lt;/span&gt;p2&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;;&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(102,102,102)"&gt;&lt;em&gt;//栈&lt;/em&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(153,51,51)"&gt;char&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;*&lt;/span&gt;p3&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;=&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(255,0,0)"&gt;"123456"&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;;&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(102,102,102)"&gt;&lt;em&gt;//"123456\0"在常量区，p3在栈上&lt;/em&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(153,51,51)"&gt;static&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(153,51,51)"&gt;int&lt;/span&gt;&nbsp;c&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;=&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,0,221)"&gt;0&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;;&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(102,102,102)"&gt;&lt;em&gt;//全局区&lt;/em&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;&nbsp;p1&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;=&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;(&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(153,51,51)"&gt;char&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;*&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;)&lt;/span&gt;malloc&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;(&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,0,221)"&gt;10&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;)&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;;&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(102,102,102)"&gt;&lt;em&gt;//p1在栈，分配的10字节在堆&lt;/em&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;&nbsp;p2&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;=&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;(&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(153,51,51)"&gt;char&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;*&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;)&lt;/span&gt;malloc&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;(&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,0,221)"&gt;20&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;)&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;;&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(102,102,102)"&gt;&lt;em&gt;//p2在栈，分配的20字节在堆&lt;/em&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;&nbsp;strcpy&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;(&lt;/span&gt;p1&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;,&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(255,0,0)"&gt;"123456"&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;)&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;;&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(102,102,102)"&gt;&lt;em&gt;//"123456"放在常量区，编译器可能会优化为和p3的指向同一块区域&lt;/em&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(177,177,0)"&gt;return&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,0,221)"&gt;0&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;}&lt;/span&gt;&nbsp;&nbsp;</li> 
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 <ol style="margin:0px 0px 1px 45px!important; padding:0px; border:none; list-style-position:initial; background-color:rgb(255,255,255); color:rgb(0,204,0)"> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(128,128,128)"&gt;&lt;em&gt;/*&nbsp;例2&nbsp;main2.c&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> *&nbsp;演示C语言中的内存分配。&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> */&lt;/em&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;#include&nbsp;&lt;stdio.h&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(102,102,102)"&gt;&lt;em&gt;//返回char型指针&lt;/em&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(153,51,51)"&gt;char&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;*&lt;/span&gt;f&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;(&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;)&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;{&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(102,102,102)"&gt;&lt;em&gt;//s数组存放于栈上&lt;/em&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(153,51,51)"&gt;char&lt;/span&gt;&nbsp;s&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;[&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,0,221)"&gt;4&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;]&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;=&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;{&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(255,0,0)"&gt;'1'&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;,&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(255,0,0)"&gt;'2'&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;,&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(255,0,0)"&gt;'3'&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;,&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(255,0,0)"&gt;'0'&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;}&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(177,177,0)"&gt;return&lt;/span&gt;&nbsp;s&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;;&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(102,102,102)"&gt;&lt;em&gt;//返回s数组的地址，但程序运行完s数组就被释放了&lt;/em&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;}&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(153,51,51)"&gt;int&lt;/span&gt;&nbsp;main&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;(&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;)&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;{&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(153,51,51)"&gt;char&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;*&lt;/span&gt;s&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;&nbsp;s&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;=&lt;/span&gt;&nbsp;f&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;(&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;)&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;&nbsp;&lt;a&nbsp;target="_blank"&nbsp;href="http://www.opengroup.org/onlinepubs/009695399/functions/printf.html"&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(34,85,136);&nbsp;text-decoration:none"&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,0,102)"&gt;printf&lt;/span&gt;&lt;/a&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;(&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(255,0,0)"&gt;"%s"&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;,&lt;/span&gt;&nbsp;s&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;)&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;;&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(102,102,102)"&gt;&lt;em&gt;//打印出来乱码。因为s所指向地址已经没有数据&lt;/em&gt;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &nbsp;&nbsp;&nbsp;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(177,177,0)"&gt;return&lt;/span&gt;&nbsp;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,0,221)"&gt;0&lt;/span&gt;&lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(51,153,51)"&gt;;&lt;/span&gt;&nbsp;&nbsp;</li> 
 <li style="margin:0px!important; padding:0px 3px 0px 10px!important; border-style:none none none solid; border-left-width:3px; border-left-color:rgb(153,153,153); list-style:decimal-leading-zero outside; background-color:rgb(85,85,85); color:rgb(255,153,153); line-height:18px"> &lt;span&nbsp;style="margin:0px;&nbsp;padding:0px;&nbsp;color:rgb(0,153,0)"&gt;}&lt;/span&gt;&nbsp;&nbsp;</li> 
 </ol> 
 </div> </td> 
 </tr> 
 </tbody> 
</table>

C++五大内存分区:  
在C++中，内存分成5个区，他们分别是堆、栈、自由存储区、全局/静态存储区和常量存储区。  
栈，就是那些由编译器在需要的时候分配，在不需要的时候自动清楚的变量的存储区。里面的变量通常是局部变量、函数参数等。  
堆，就是那些由new分配的内存块，他们的释放编译器不去管，由我们的应用程序去控制，一般一个new就要对应一个delete。如果程序员没有释放掉，那么在程序结束后，操作系统会自动回收。  
自由存储区，就是那些由malloc等分配的内存块，他和堆是十分相似的，不过它是用free来结束自己的生命的。  
全局/静态存储区，全局变量和静态变量被分配到同一块内存中，在以前的C语言中，全局变量又分为初始化的和未初始化的，在C++里面没有这个区分了，他们共同占用同一块内存区。  
常量存储区，这是一块比较特殊的存储区，他们里面存放的是常量，不允许修改（当然，你要通过非正当手段也可以修改，而且方法很多）

《Unix环境高级编程》（著名的APUE）中提出：  
C程序的内存布局：Text，Data，BSS，Stack, Heap.  
Text是程序的代码段。  
Data是程序中初始化了的全局、静态数据变量。  
BSS是程序中未初始化的全局、静态数据变量。即使全局、静态数据变量初始化为0仍然是属于BSS段。（未初始化的数据段）  
Stack是程序中的局部变量，由高地址到低地址向下增长。  
Heap是malloc调用动态分配的内存，由低地址到高地址向上增长。

根据网上别人的观点结合自己的测试，得出的结论：  
1、 经过初始化的全局变量和静态变量保存在数据段中。  
2、 未经初始化的全局变量和静态变量保存在BSS段。  
3、 函数内部声明的局部变量保存在堆栈段(栈)中，函数调用相关信息也在栈中。  
4、 const修饰的全局变量保存在文本段中，const修饰的局部变量保存在堆栈段中。  
5、 字符串常量保存在文本段中。

查看各段的大小用size命令：size test.out (test.out为编译连接后的可执行文件)，可以查看到text、data、bss段的大小。

堆与栈的讨论：  
管理方式：  
堆中资源由程序员控制（容易产生memory leak）。  
栈资源由编译器自动管理，无需手工控制。

系统响应：  
对于堆，应知道系统有一个记录空闲内存地址的链表，当系统收到程序申请时，遍历该链表，寻找第一个空间大于申请空间的堆结点，删除空闲结点链表中的该结点，并将该结点空间分配给程序（大多数系统会在这块内存空间首地址记录本次分配的大小，这样delete才能正确释放本内存空间，另外系统会将多余的部分重新放入空闲链表中）。  
对于栈，只要栈的剩余空间大于所申请空间，系统为程序提供内存，否则报异常提示栈溢出。

空间大小：  
堆大小受限于计算机系统中有效的虚拟内存（32bit系统理论上是4G），所以堆的空间比较灵活，比较大。  
栈大小是操作系统/编译器预定好的。

碎片问题：  
对于堆，频繁的new/delete会造成大量碎片，使程序效率降低。  
对于栈，它是一个先进后出的队列，进出一一对应，不会产生碎片。

生长方向：  
堆向上，向高地址方向增长。  
栈向下，向低地址方向增长。

分配方式：  
堆都是动态分配（没有静态分配的堆）。  
栈有静态分配和动态分配，静态分配由编译器完成（如局部变量分配），动态分配由alloca函数分配，但栈的动态分配的资源由编译器进行释放，无需程序员实现。

分配效率：  
堆由C/C++函数库提供，机制很复杂。所以堆的效率比栈低很多。  
栈是极其系统提供的数据结构，计算机在底层对栈提供支持，分配专门寄存器存放栈地址，栈操作有专门指令。

对C内存的深入研究(根据《C专家编程》)以及实例和结论，一篇很好的文章，见：

http://blog.csdn.net/chgaowei/archive/2010/03/03/5340796.aspx

Linux上内存管理：

http://www.kerneltravel.net/journal/v/mem.htm