asked on

try... catch problem

Hello Experts!

Please have a look at the code below.

I expect to catch exception, instead I get exception risen by vector code and it crashes my application.

What do I do wrong here?

Thank you

panJames

#include <vector>
#include <iostream>
#include <exception>

using namespace std;

void main()
{
	int a;
	std::vector<int> abc;

	abc.push_back(1);
	abc.push_back(2);

	try
	{
		a = abc[2];
	}
	catch (exception& e)
	{
		cout << e.what();

	}

}

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Guy Hengel [angelIII / a3]

you need to put the try larger:

#include <vector>
#include <iostream>
#include <exception>

using namespace std;

void main()
{
        try
        {
        int a;
        std::vector<int> abc;

        abc.push_back(1);
        abc.push_back(2);

                a = abc[2];
        }
        catch (exception& e)
        {
                cout << e.what();

        }

}

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kaufmed

To further angelIII's comment, you only reserved the space--you didn't actually initialize it, so you are trying to call a method on a null object, hence the exception.

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Infinity08

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panJames

ASKER

@angelIII:

1. Why do I need larger try{} selection? Thought that I need to make my try{} where I expect it to crash...
2. It does not help anyway. Program never comes to line:

cout << e.what();

panJames

ASKER

@kaufmed: I know it.

panJames

kaufmed

>> @kaufmed: I know it.

Uhhh... then you have your answer = )

Calling a method on an uninstantiated object raises an exception.

panJames

ASKER

@Infinity08:

I am confused now.

My understanding of try{} was that if anything wrong happens inside try{} then exception is thrown and all I need to do is to catch it (like in Delphi).

So C++ program does not have such functionality?

How can I catch something simple like:

int a = 12;
int b = 0;
int c;

try
{
c = a / b;
}

panJames

Infinity08

>> My understanding of try{} was that if anything wrong happens inside try{} then exception is thrown and all I need to do is to catch it (like in Delphi).

No, not anything. Anything that throws a C++ exception will be caught if you have an appropriate catch handler. But divisions by 0 or segmentation faults eg. won't.

>> So C++ program does not have such functionality?

Some compilers might add it as an extension, but it's not generally available no.