Rethrow An Exception | Exception Handling | C++ Tutorials

It is possible that a single catch block may not handle an exception completely. In such a situation, the catch block on receiving an exception must pass it to another catch block by rethrowing an exception. The rethrowing expression takes the following from,

                                                    throw ;

The rethrow expression can only appear in the catch block from where it is implicitly propagated to outer try/catch sequence and is caught by that catch block which has the same type parameter. The following program illustrate how an exception is rethrown and caught.

1. #include<iostream.h>
2. #include<conio.h>
3. void funchandler()
4. {
5.    try
6.    {  throw 10; }
7.    catch(int i)
8.    {
9.       cout<<"caught exception  inside function";
10.       throw;
11.    }
12. }
13. int main()
14. {
15.    cout<<"start of mail()\n";
16.    try
17.    {
18.       funchandler();
19.    }
20.    catch(int i)
21.    {
22.       cout<<"Rethrown exception caught is main()\n";
23.    }
24.    cout<<"End of main()";
25.    return 0;
26. }

Output

Start of main()
caught exception inside function
Rethrown exception caught in main()
End of main()

Tags : Exception handling in C++, C++ tutorials, Exception handling Tutorials