C/C++学习----第六章异常处理

桃扇骨 2022-09-17 16:16 58阅读 0赞

# 第六章 异常处理 #

确定程序出错时，执行的代码，称之为异常处理程序。三个关键词：try, throw 和catch。程序中的异常都有一个唯一的名字，可以通过创建异常类来定义一个异常。在程序发生异常时，许多情况下需要指定关于该异常的附加信息：一种解决方案是向以常类中加入成员变量，以及把参数赋予成员的构造函数，当程序捕获到这个异常时，通过检查它的成员变量，以确定有关该异常起因的更多信息。

class myexcept\{

public:

int value;

myexcept(int i)\{

value =i;

\}; //定义异常类

function()\{

throw myexcept(5);

void main()

try\{

function();

catch (out\_of\_memory & e)

cout<<”exception value is ”<<e.value;//异常处理过程

**在一个catch中捕获多处异常：**

enumfileexception \{ open, read, write, close\};

voidfunc()

throwfileexception(open);

voidmain()

try \{

func();

catch(fileexceptionvalue)

switch(value)

caseopen :

cout<<"open error"<<endl; break;

caseread:

cout<<" read error"<<endl; break;

casewrite:

cout<<" write error"<<endl; break;

caseclose:

cout<<" close error"<<endl; break;

default: break;

exit(1);

标准异常exception类结构图：

<table> 
 <tbody> 
  <tr> 
   <td style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"> 
    <div> 
     <p style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center"><span><font>exception</font></span></p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <tbody> 
  <tr> 
   <td style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"> 
    <div> 
     <p style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center"><span><font>bad_alloc</font></span></p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <tbody> 
  <tr> 
   <td style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"> 
    <div> 
     <p style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center"><span><font>bab_typeid</font></span></p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <tbody> 
  <tr> 
   <td style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"> 
    <div> 
     <p style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center"><span><font>logic_error</font></span></p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <tbody> 
  <tr> 
   <td style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"> 
    <div> 
     <p style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center"><span><font>ios::base_failure</font></span></p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <tbody> 
  <tr> 
   <td style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"> 
    <div> 
     <p style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center"><span><font>runtime_error</font></span></p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <tbody> 
  <tr> 
   <td style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"> 
    <div> 
     <p style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center"><span><font>bab_exception</font></span></p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <tbody> 
  <tr> 
   <td style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"> 
    <div> 
     <p style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center"><span><font>domain_error</font></span></p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <tbody> 
  <tr> 
   <td style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"> 
    <div> 
     <p style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center"><span><font>invalid_argument</font></span></p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <tbody> 
  <tr> 
   <td style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"> 
    <div> 
     <p style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center"><span><font>length_error</font></span></p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <tbody> 
  <tr> 
   <td style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"> 
    <div> 
     <p style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center"><span><font>out_of_range</font></span></p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <tbody> 
  <tr> 
   <td style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"> 
    <div> 
     <p style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center"><span><font>range_error</font></span></p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <tbody> 
  <tr> 
   <td style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"> 
    <div> 
     <p style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center"><span><font>overfloe_error</font></span></p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

<table> 
 <tbody> 
  <tr> 
   <td style="BORDER-RIGHT: #d4d0c8; BORDER-TOP: #d4d0c8; BORDER-LEFT: #d4d0c8; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent"> 
    <div> 
     <p style="MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: center"><span><font>underflow_error</font></span></p> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

当new 失败时，抛出bad\_alloc异常；当程序非预期的异常时，抛出bab\_exception异常；