Char array difficulty

I'm unable to enforce char array bounds for some reason. Take a look at the following code (iostream was giving me a hard time so I used the C headers)

Code:

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#include <stdio.h>
#include <string.h>

class OOBException {};

class Test
{
    public:
        char *strtest;
};

int main()
{
    Test *test = new Test();
    test->strtest = new char[14];
    try
    {
        gets(test->strtest);
        printf("%s", test->strtest);
    }
    catch (OOBException e)
    {
        printf("exception raised\n");
    }

    return 0;
}

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It compiles okay, but I'm trying to crash it with an exception when I enter more than 13 characters. It simply executes the try clause with no problems no matter what. If I'm inputting more than 13 characters, why doesn't it crash since it goes beyond array boundaries?

And what bizarre magic do you expect to cause gets() to throw an OOBException if it goes out of bounds?

Welcome to the wonderful world of C and undefined behavior that you've now experienced in C++.

Quote:

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Originally Posted by brewbuck

And what bizarre magic do you expect to cause gets() to throw an OOBException if it goes out of bounds?

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Hmm... alright then. I take it C++ just writes the extra characters to the memory beyond the array boundaries? This, of course, overwrites anything occupying the memory, but just asking.

Sorry, I've had to take a Java prereq course and now my mind is practically poisoned by it.

Quote:

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Originally Posted by Chris87

Hmm... alright then. I take it C++ just writes the extra characters to the memory beyond the array boundaries? This, of course, overwrites anything occupying the memory, but just asking.

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Yes.

Quote:

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Sorry, I've had to take a Java prereq course and now my mind is practically poisoned by it.

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Even in Java, why would you expect some custom exception you've defined to get thrown?

One thing doesn't make sense though. If it writes to the array boundaries as well as extra characters beyond it, how come printf() echoes the entire input rather than just the array boundary? Shouldn't the extra characters be a memory leak until termination?

Quote:

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Originally Posted by Chris87

One thing doesn't make sense though. If it writes to the array boundaries as well as extra characters beyond it, how come printf() echoes the entire input rather than just the array boundary? Shouldn't the extra characters be a memory leak until termination?

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No. In C, a string's length is not directly specified, but rather implied by the presence of a terminating '\0' character. So printf() will continue printing characters until it sees this "end of string" marker, which was placed there by the previous (overflowing) operation.

You've got to expunge this idea of "boundaries" from your thinking. There are no boundaries. There are only places where if you touch it, it explodes. But you don't know this until you touch it.

silly me..

Quote:

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Originally Posted by Chris87

silly me..

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Well, I won't lie about it -- C and C++ are an awful lot more "unsafe" than Java in this regard.

Quote:

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Originally Posted by brewbuck

Well, I won't lie about it -- C and C++ are an awful lot more "unsafe" than Java in this regard.

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Well, I know that. I'm aware of how disasterous C is, but I'm also aware of how powerful it is as well. Java is cooshy-cooshy and isn't suitable for anything but web applications and small programs. If you've tried the game Runescape, you'll see why...

I got frustrated with Java even, because I find pointers a necessity in my work, as well as bitwise operations. Plus C headers provide a means to skim over the public contents of an implementation, for humans and for the compiler. Java packs the declaration and definition together and it gets very annoying to read. Not to mention I don't want everything in classes. Yes, I want to use classes but not all the time.

Blaming a language on one program isn't the best idea. You have to focus on knowing the strengths and weaknesses of the language in question, along with understanding the paradigms that the language writers intended for you to use.

Why would you want a C-style pointer in Java? Are you sure you haven't gone against the intended paradigm, losing out on the strengths of Java?

It seems you lack the ability to discipline yourself to write code the way you're supposed to for the given language. You want pointers in Java, so you switch to C++. You can't figure out C++, so you mix a bunch of C code.

Learn the languages for how they are supposed to be used. Things will be much easier for you. ;)

Quote:

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Originally Posted by MacGyver

Blaming a language on one program isn't the best idea. You have to focus on knowing the strengths and weaknesses of the language in question, along with understanding the paradigms that the language writers intended for you to use.

Why would you want a C-style pointer in Java? Are you sure you haven't gone against the intended paradigm, losing out on the strengths of Java?

It seems you lack the ability to discipline yourself to write code the way you're supposed to for the given language. You want pointers in Java, so you switch to C++. You can't figure out C++, so you mix a bunch of C code.

Learn the languages for how they are supposed to be used. Things will be much easier for you. ;)

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Well, I did say Java was good for web/small applications, but as far as I know, it's just that. Though, in my case, I'd feel a bit uncomfortable using it with it's safeguards at the cost of low-level functionality.