What is wrong with this code? - Computer Programmers, Programming Forum

Abbash · #1 02-25-2010

Hi All,

This is my very first thread in this forum.

Could anybody help me with this code:

class Foo
{
char* buf;
public:
Foo(const char* b = "default")
{
if(b)
{
buf = new char[strlen(b) + 1];
strcpy(buf, b);
}
else
buf = 0;
}

~Foo() { delete[] buf; }
};

Foo func(Foo f)
{
return f;
}

Referring to the code above, when the func is called, the program may crash or exhibit unexpected behaviour, what is the reason for this problem?

Many thanks
Abbash

Dumaju · #2 03-04-2010

Could you provide the error messages? It may also be helpful if you pasted your code whilst wrapping it in [code][/code] tags.

Abbash · #3 03-12-2010

Quote:

Dumaju originally posted:

Could you provide the error messages? It may also be helpful if you pasted your code whilst wrapping it in [code][/code] tags.

This was an interview question that I had to do and did not know the answer. It say "This program may crash..." but then again it may not crash. The question is by looking at the code we should be able to determin what is wrong with this code.

Code:

class Foo
{
    char* buf;
public:
    Foo(const char* b = "default")
    {
        if(b)
        {
            buf = new char[strlen(b) + 1];
            strcpy(buf, b);
        }
        else
            buf = 0;
    }

    ~Foo() { delete[] buf; }
};

Foo func(Foo f)
{
    return f;
}

Dumaju · #4 03-13-2010

My guess would be that you may be expecting the function to return a reference, when it's really returning by value? I'll check it out a bit more when I've downloaded and installed Visual Studio.

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