Exceptions/Catch an exception thrown in a nested call: Difference between revisions

=={{header|C++}}==

First exception will be caught and message will be displayed,

second will be caught by the default exception handler,

which as required by the C++ Standard, will call terminate(),

aborting the task, typically with an error message.

<lang cpp>#include <iostream>

class U0 {};

class U1 {};

void baz(int i)

{

if (!i) throw U0();

else throw U1();

}

void bar(int i) { baz(i); }

void foo()

{

for (int i = 0; i < 2; i++)

{

try {

bar(i);

} catch(U0 e) {

std::cout<< "Exception U0 caught\n";

}

}

}

int main() {

foo();

std::cout<< "Should never get here!\n";

return 0;

}</lang>

Result:

<pre>

Exception U0 caught

This application has requested the Runtime to terminate it in an unusual way.

</pre>

The exact behavior for an uncaught exception is implementation-defined.

=={{header|EGL}}==

{{incorrect|EGL|calls to bar() from foo should be equivalent. Second call can't catch anything.}}

<lang EGL>record U0 type Exception

end

record U1 type Exception

end

program Exceptions

function main()

foo();

end

function foo()

try

bar();

onException(ex U0)

SysLib.writeStdout("Caught a U0 with message: '" :: ex.message :: "'");

end

bar();

end

function bar()

baz();

end

firstBazCall boolean = true;

function baz()

if(firstBazCall)

firstBazCall = false;

throw new U0{message = "This is the U0 exception"};

else

throw new U1{message = "This is the U1 exception"};

end

end

end</lang>

{{out}}

<pre>

Caught a U0 with message: 'This is the U0 exception'

This is the U1 exception

</pre>

=={{header|Raku}}==

(formerly Perl 6)

{{trans|Perl}}

<lang perl6>sub foo() {

for 0..1 -> $i {

bar $i;

CATCH {

when /U0/ { say "Function foo caught exception U0" }

}

}

}

sub bar($i) { baz $i }

sub baz($i) { die "U$i" }

foo;</lang>

{{out}}

<pre>Function foo caught exception U0

U1

in sub baz at catch:12

in sub bar at catch:10

in sub foo at catch:4

in block at catch:14</pre>