举例说明自定义C++异常处理的实例
例1：自定义一个继承自excepton的异常类myException
C++标准中，定义在<stdexcept>中的任何异常类都派生自exception Class，本例也只是简单地由exception继承，在try段抛出一个异常并捕捉。代码如下：
/*++ test.cpp
version:1.0
decript:define a exception class named myException
derived from base class exception
which is declared in <exception>
created:2011-08-14
author: btwsmile
--*/
#include<exception>
#include<iostream>
using namespace std;
//customized exception class 'myException'
class myException:public exception
{
public:
myException():exception("ERROR! Don't divide a number by integer zero.n")
{
}
};
//entry of the application
int main()
{
int x=100,y=0;
try
{
if(y==0) throw myException();
else cout<<x/y;
}
catch(myException& me)
{
cout<<me.what();
}
system("pause");
return 0;
}
结果如下：
ERROR! Don't divide a number by integer zero.
请按任意键继续. . .
显然，异常被捕捉到了。此处需要说明的是，VC对异常处理类exception进行了扩展，本例之所以能够使用exception("ERROR!....")的初始化方法正出于这样的原因，C++标准是不允许这样做的。
与此同时，VC又没有遵循标准，有力地支持terminate和unexpected，它只保留了语法，却在编译运行时不提供支持。为了结合terminate和unexpected更加深入了解C++的异常处理，下面的例子采用Dev cpp IDE实现。
例2：依照C++标准实现自定义异常类myException并将throw语句封装到函数check()中涉及到的更改正如标题所述，（1）重写基类的what()函数，返回错误信息；（2）将throw myException()封装到check()函数中；(3)允许check()函数抛出myException类型的异常。代码如下：
/*++ test.cpp
version:1.1
decript:define a exception class named myException
according to C++ standard,
derived from base class exception
which is declared in <exception>
!also,encapusulate throw into a function
created:2011-08-14
author: btwsmile
--*/
#include<exception>
#include<iostream>
using namespace std;
//customized exception class 'myException'
class myException:public exception
{
public:
const char* what()const throw()//#1
{
return "ERROR! Don't divide a number by integer zero.n";
}
};
void check(int y) throw(myException)//#2
{
if(y==0) throw myException();
}
//entry of the application
int main()
{
int x=100,y=0;
try
{
check(y);
cout<<x/y;
}
catch(myException& me)
{
cout<<me.what();
}
system("pause");
return 0;
}
