异常处理结构

  1. #include<bits/stdc++.h>
  2. using namespace std;
  4. /**
  5.  * 异常处理
  6.  * 注意：类型必须完全匹配
  7.  * */
  9. int main() {
  10.     cout<<"1--before try block"<<endl;
  11.     try {
  12.         cout<<"2--inside try block"<<endl;
  13.         throw 10;
  14.         cout<<"3--after throw"<<endl;
  15.     }
  16.     catch(int i) {
  17.         cout<<"4--in catch block 1 errcode is"<<i<<endl;
  18.     }
  19.     catch(char *s) {
  20.         cout<<"5-in catch block 2 errcode is"<<s<<endl;
  21.     }
  22.     cout<<"6--after catch"<<endl;
  23.     return 0;
  24. }

在函数中处理异常

  1. #include<bits/stdc++.h>
  2. using namespace std;
  4. /**
  5.  * 在函数中处理异常
  6.  * */
  7. void temperature(int t) {
  8.     if(t == 100) {
  9.         throw "hot";
  10.     }
  11.     else if(t == 0) {
  12.         throw "cold";
  13.     }
  14.     else {
  15.         cout<<"temperature is: "<<t<<endl;
  16.     }
  17. }
  18. int main() {
  19.     try {
  20.         temperature(0);
  21.         temperature(10);
  22.         temperature(100);
  23.     }
  24.     catch(const char *s) {
  25.         cout<<s<<endl;
  26.     }
  27.     return 0;
  28. }

捕获所有异常

  1. #include<bits/stdc++.h>
  2. using namespace std;
  4. /**
  5.  * 捕获所有异常
  6.  * */
  7. void errhandler(int n) throw() {
  8.     try {
  9.         if(n == 1) {
  10.             throw n;
  11.         }
  12.         if(n == 2) {
  13.             throw "dx";
  14.         }
  15.         if(n == 3) {
  16.             throw 1.1;
  17.         }
  18.     }
  19.     catch(...) {
  20.         cout<<"catch an exception"<<endl;
  21.     }
  22. }
  23. int main() {
  24.     errhandler(1);
  25.     errhandler(2);
  26.     errhandler(3);
  27.     return 0;
  28. }

嵌套异常捕获

  1. #include<bits/stdc++.h>
  2. using namespace std;
  4. /**
  5.  * 嵌套异常捕获
  6.  * */
  7. void fc( ){
  8.     try{
  9.         throw "help";
  10.     }
  11.     catch (int x) {
  12.         cout<< "in fc int handler"<<endl;
  13.     }   
  15.     try {
  16.         cout<<"no error handler"<<endl;
  17.     }
  18.     catch (const char *px) {
  19.         cout<<"in fc char * handler"<<endl;
  20.     } 
  21. }
  22. void fb() {
  23.     int *q = new int(10);
  24.     try {
  25.         fc();
  26.         cout<<"return form fc(0)"<<endl;
  27.     }
  28.     catch(...) {
  29.         delete []q;
  30.         throw;
  31.     }
  33. }
  34. void fa() {
  35.     char *p = new char[10];
  36.     try {
  37.         fb();
  38.         cout<<"return form fb(0)"<<endl;
  39.     }
  40.     catch(...) {
  41.         delete []p;
  42.         throw;
  43.     }
  44. }
  45. int main() {
  46.     try {
  47.         fa();
  48.         cout<<"return form fa"<<endl;
  49.     }
  50.     catch(...) {
  51.         cout<<"in main"<<endl;
  52.     }
  53.     cout<<"end"<<endl;
  54.     return 0;
  55. }

构造函数异常

  1. #include<bits/stdc++.h>
  2. using namespace std;
  4. /**
  5.  * 构造函数异常
  6.  * */
  8. class A {
  9.     int a;
  10. public:
  11.     A(int i = 0):a(i) {
  13.     }
  14.     ~A() {
  15.         cout<<"in a destructor"<<endl;
  16.     }
  17. };
  19. class B {
  20.     A obj[3];
  21.     double *pb[10];
  22. public:
  23.     B(int k) {
  24.         cout<<"in b constructor"<<endl;
  25.         for(int i = 0; i < 10; i++) {
  26.             pb[i] = new double[20000000];
  27.             if(pb[i] == 0) {
  28.                 throw i;
  29.             }
  30.             else {
  31.                 cout<<"allocated 20000000 doubles in pb["<<i<<"]"<<endl;
  32.             }
  33.         }
  34.     }
  35. };
  37. int main() {
  38.     try {
  39.         B b(2);
  40.     }
  41.     catch (int e) {
  42.         cout<<"catch an exception when allocated pb["<<e<<"]"<<endl;
  43.     }
  44.     return 0;
  45. }

异常类

  1. #include<bits/stdc++.h>
  2. using namespace std;
  4. /**
  5.  * 异常类
  6.  * */
  7. const int MAX = 3;
  8. class Full {
  10. };
  12. class Empty {
  14. };
  16. class Stack {
  17.     int s[MAX];
  18.     int top;
  19. public:
  20.     void push(int a) {
  21.         if(top >= MAX-1) {
  22.             throw Full();
  23.         }
  24.         s[++top] = a;
  25.     }
  26.     int pop() {
  27.         if(top < 0) {
  28.             throw Empty();
  29.         }
  30.         return s[top--];
  31.     }
  32.     Stack() {
  33.         top = -1;
  34.     }
  35. };
  36. int main() {
  37.     Stack s;
  38.     try {
  39.         s.push(10);
  40.         s.push(20);
  41.         s.push(30);
  42.         // s.push(40); // 引起栈满异常
  44.         cout<<s.pop()<<endl;
  45.         cout<<s.pop()<<endl;
  46.         cout<<s.pop()<<endl;
  47.         cout<<s.pop()<<endl;
  48.     }
  49.     catch(Full) {
  50.         cout<<"Exception Stack Full"<<endl;
  51.     }
  52.     catch(Empty) {
  53.         cout<<"Exception Stack Empty"<<endl;
  54.     }
  55.     return 0;
  56. }

异常对象

  1. #include<bits/stdc++.h>
  2. using namespace std;
  4. /**
  5.  * 异常对象
  6.  * */
  7. const int MAX = 3;
  8. class Full {
  9.     int a;
  10. public:
  11.     Full(int i):a(i) {
  13.     }
  14.     int getValue() {
  15.         return a;
  16.     }
  17. };
  18. class Empty {
  20. };
  21. class Stack {
  22.     int s[MAX];
  23.     int top;
  24. public:
  25.     Stack() {
  26.         top = -1;
  27.     }
  28.     void push(int a) {
  29.         if(top >= MAX-1) {
  30.             throw Full(a);
  31.         }
  32.         s[++top] = a;
  33.     }
  34.     int pop() {
  35.         if(top < 0) {
  36.             throw Empty();
  37.         }
  38.         return s[top--];
  39.     }
  40. };
  41. int main() {
  42.     Stack s;
  43.     try {
  44.         s.push(10);
  45.         s.push(20);
  46.         s.push(30);
  47.         s.push(40);
  48.     }  
  49.     catch (Full e) {
  50.         cout<<"Exception:Stack Full"<<endl;
  51.         cout<<"The Value not push in stack:"<<e.getValue()<<endl;
  52.     }
  54.     return 0;
  55. }

派生异常类

  1. #include<bits/stdc++.h>
  2. using namespace std;
  4. /**
  5.  * 派生异常类
  6.  * */
  7. class BasicException {
  8. public:
  9.     char *Where() {
  10.         return "BasicException";
  11.     }
  12. };
  13. class FileSysException: public BasicException {
  14. public:
  15.     char *Where() {
  16.         return "FileSysException";
  17.     }
  18. };
  19. class FileNotFound: public FileSysException {
  20. public:
  21.     char *Where() {
  22.         return "FileNotFound";
  23.     }
  24. };
  26. class DiskNotFound: public FileSysException {
  27. public:
  28.     char * Where() {
  29.         return "DiskNotFound";
  30.     }
  31. };
  32. int main() {
  33.     try {
  34.         throw FileSysException();
  35.     }
  36.     catch(DiskNotFound p) {
  37.         cout<<p.Where()<<endl;
  38.     }
  39.     catch(FileNotFound p) {
  40.         cout<<p.Where()<<endl;
  41.     }
  42.     catch(FileSysException p) {
  43.         cout<<p.Where()<<endl;
  44.     }
  45.     catch(BasicException p) {
  46.         cout<<p.Where()<<endl;
  47.     }
  49.     try {
  50.         throw DiskNotFound();
  51.     }
  52.     catch(BasicException p) {
  53.         cout<<p.Where()<<endl;
  54.     }
  55.     catch(FileSysException p) {
  56.         cout<<p.Where()<<endl;
  57.     }
  58.     catch(DiskNotFound p) {
  59.         cout<<p.Where()<<endl;
  60.     }
  61.     catch(FileNotFound p) {
  62.         cout<<p.Where()<<endl;
  63.     }
  64.     return 0;
  65. }

多态捕获派生类异常

  1. #include<bits/stdc++.h>
  2. using namespace std;
  4. /**
  5.  * 多态捕获派生异常类
  6.  * */
  7. class BasicException {
  8. public:
  9.     virtual char *Where() {
  10.         return "BasicException";
  11.     }
  12. };
  13. class FileSysException: public BasicException {
  14. public:
  15.     char *Where() {
  16.         return "FileSysException";
  17.     }
  18. };
  19. class FileNotFound: public FileSysException {
  20. public:
  21.     char *Where() {
  22.         return "FileNotFound";
  23.     }
  24. };
  26. class DiskNotFound: public FileSysException {
  27. public:
  28.     char * Where() {
  29.         return "DiskNotFound";
  30.     }
  31. };
  32. int main() {
  33.     try {
  34.         throw FileSysException();
  35.     }
  36.     catch(BasicException &p) {
  37.         cout<<p.Where()<<endl;
  38.     }
  40.     try {
  41.         throw DiskNotFound();
  42.     }
  43.     catch(BasicException &p) { // 注意这里必须加引用才能体现多态和虚函数的性质，否则会调用基类的异常处理
  44.         cout<<p.Where()<<endl;
  45.     }
  46.     return 0;
  47. }