Multiple Catch Statements - Catching all Exceptions

In some situations the program segment has more than one condition to throw an exception.In such case more than one catch blocks can be associated with a try block as shown below

try

{//try block

}

catch(type1 arg)

{ 

//catch block1

}

catch(type 2 arg)

{

//catch block 2

}

……………..

…………….

catch (type N arg)

{

//catch block N

}

When an exception is thrown, the exception handlers are searched in order for an appropriate match. The first handler that yields a match is executed. After executing the handler, the control goes to the first statement after the last catch block for that try. When no match is found, the program is terminated.

If in some case the arguments of several catch statements match the type of an exception, then the first handler that matches the exception type is executed.

Catch All Exceptions:-

In some cases when all possible type of exceptions cannot be anticipated and may not be able to design independent catch handlers to catch them, in such situations a single catch statement is forced to catch all exceptions instead of certain type alone. This can be achieved by defining the catch statement using ellipses as follows

catch(. . .)

{

//statement for processing all exceptions

}

Example:

#include <iostream.h>

void test(int x)

{

try

{

if (x== 0) throw x; //int

if ( x== -1) throw ‘x’; //char

if ( x== 1) throw 1.0; //float

}

catch(. . .) //catch all

{

cout<<”caught an exception \n”;

}

}

int main()

{

cout<<”testing generic catch\n”;

test(-1);

test(0);

test(1);

}

The catch(. . .) can be used as a default statement along with other catch handlers so that it can catch all those exceptions that are not handled explicitly.