C++ Tutorial/Exceptions/Exception type

Catch double exception

<source lang="cpp">#include <iostream> using namespace std; int main(void) {

  try {
     cout << "Inside try block." << endl;
     throw 100;
     cout << "This will not execute.";
  }catch(double d) {
     cout << "Caught a double exception -- value is: ";
     cout << d << endl;
  }

}</source>

Catching class type exceptions

<source lang="cpp">#include <iostream>

1. include <cstring>

using namespace std; class MyException { public:

 char message[80];
 int what;
 MyException() { *message = 0; what = 0; }
 MyException(char *s, int e) {
   strcpy(message, s);
   what = e;
 }

}; int main() {

 int i;
 try {
   cout << "Enter a positive number: ";
   throw MyException("Not Positive", -1);
 }
 catch (MyException e) { // catch an error
   cout << e.message << ": ";
   cout << e.what << "\n";
 }
 return 0;

}</source>

Enter a positive number: Not Positive: -1

Catching Class Types

<source lang="cpp">#include <iostream>

1. include <cstring>

using namespace std;

class MyException { public:

 char str_what[80];
 int what;
  
 MyException() { *str_what = 0; what = 0; }
  
 MyException(char *s, int e) {
   strcpy(str_what, s);
   what = e;
 }

};

int main(){

 int i;
  
 try {
   cout << "Enter a positive number: ";
   cin >> i;
   if(i<0)
     throw MyException("Not Positive", i);
 }
 catch (MyException e) { // catch an error
   cout << e.str_what << ": ";
   cout << e.what << "\n";
 }
  
 return 0;

}</source>

Different types of exceptions can be caught

<source lang="cpp">#include <iostream> using namespace std; void f(int test) {

 try{
   if(test) 
      throw test;
   else 
      throw "Value is zero";
 }
 catch(int i) {
   cout << "Caught Exception #: " << i << "\n";
 }
 catch(const char *str) {
   cout << "Caught a string: ";
   cout << str << "\n";
 }

} int main() {

 cout << "Start\n";
 f(1);
 f(2);
 f(0);
 f(3);
 cout << "End";
 return 0;

}</source>

Start
Caught Exception #: 1
Caught Exception #: 2
Caught a string: Value is zero
Caught Exception #: 3
End"

how to restrict the types of exceptions that can be thrown from a function.

<source lang="cpp">#include <iostream> using namespace std;

void Xhandler(int test) throw(int, char, double){

 if(test==0) throw test; 
 if(test==1) throw "a"; 
 if(test==2) throw 123.23; 

}

int main() {

 cout << "start\n";
  
 try{
   Xhandler(0); 
 }
 catch(int i) {
   cout << "Caught an integer\n";
 }
 catch(char c) {
   cout << "Caught char\n";
 }
 catch(double d) {
   cout << "Caught double\n";
 }
  
 cout << "end";
  
 return 0;

}</source>