异常

try检测异常

throw抛出

catch处理异常

C++处理异常

 1 #include <iostream>
 2 
 3 class wrong//表示错误类型
 4 {
 5 
 6 };
 7 
 8 int intdiv(int a, int b)
 9 {
10     try
11     {
12         if (!b)
13         {
14             throw wrong();
15         }
16 
17         int c = a / b;
18         return a / b;
19     }
20     catch (wrong)
21     {
22         std::cout << "除法异常已经处理" << std::endl;
23         return -1;
24     }
25 }
26 
27 void main()
28 {
29     int x, y;
30     std::cin >> x >> y;
31 
32     std::cout << intdiv(x, y) << std::endl;
33 }

类中异常

 1 #include <iostream>
 2 
 3 class box
 4 {
 5 public:
 6     box(int data) :a(data)
 7     {
 8         std::cout << "开始构造" << std::endl;
 9 
10         if (data < 100)
11         {
12             throw small();
13         }
14         else if (data > 10000)
15         {
16             throw big();
17         }
18     }
19     class big {};
20     class small {};
21 private:
22     int a;
23 };
24 
25 void main()
26 {
27     try
28     {
29         box newbox(200);
30     }
31     catch (box::big)
32     {
33         std::cout << "长度太长" << std::endl;
34     }
35     catch (box::small)
36     {
37         std::cout << "长度太短" << std::endl;
38     }
39 }

异常类的派生

适用于处理违反了2个规则的异常

 1 #include <iostream>
 2 #include <string>
 3 
 4 class box//正方体
 5 {
 6 public:
 7     box(int data)
 8     {
 9         std::cout << "开始构造" << std::endl;
10 
11         if (data == 0)
12         {
13             zero z1(22);
14             z1.seterror(21);
15 
16             throw z1;
17         }
18         else if (data > 0 && data<100)
19         {
20             throw small();
21         }
22         else  if (data>10000)
23         {
24             throw big();
25         }
26         else if (data > 100 && data < 10000)
27         {
28             a = data;
29         }
30         else
31         {
32             throw wrong{};
33         }
34     }
35     
36     int  gettiji()
37     {
38         return  a*a*a;
39     }
40 
41     class wrong {};
42     class big {};
43     class small {};
44 
45     class zero :public small//两种错误的处理方式都接受
46     {
47     public:
48         int errorcode;
49         zero(int i) :errorcode(i)
50         {
51 
52         }
53         void  seterror(int i)
54         {
55             errorcode = i;
56         }
57     };
58 private:
59     int a;//变长
60 };
61 
62 void main()
63 {
64 
65     try
66     {
67         box newbox(0);
68     }
69 
70     catch (box::wrong)
71     {
72         std::cout << "正方体长度异常" << std::endl;
73     }
74     catch (box::big)
75     {
76 
77         std::cout << "正方体长度太长" << std::endl;
78     }
79     catch (box::zero w)
80     {
81         if (w.errorcode == 22)
82         {
83             std::cout << "22号错误正方体长度不可以为0" << std::endl;
84         }
85         else
86         {
87             std::cout << "fei22号错误正方体长度不可以为0" << std::endl;
88         }
89 
90     }
91     catch (box::small)
92     {
93         std::cout << "正方体长度taiduan" << std::endl;
94     }
95 }

MFC处理异常

 1 void openfile()
 2 {
 3     TRY
 4     {
 5         CFile file(_T("F:\users\123.txt"), CFile::modeRead);//尝试动作，如果异常，抛出异常
 6     }
 7         CATCH(CFileException, e)//文件的异常
 8     {
 9         if (e->m_cause == CFileException::fileNotFound)
10         {
11             cout << "文件不存在，请认真检查";
12         }
13     }
14     END_CATCH
15 }