Dealing with chars in C++ (without std::string)

Question

I have this code:

char* value = "abcdefg";

char* secondValue = value;

The second value will get the addres of value ok? If I delete "value" the secondValue won't be available am I right?

so I should do:

char* value = "abcdefg";
secondValue = new char[strlen(value)];
strcpy(secondValue, value);

so If I delete "value" no problem.

And finally to dealloc the secondValue I should do:

delete[] secondValue;

am I right?

Answer 1

There are two issues with what you wrote:

1. You cannot delete char *value = "abcdefg";, as it is not allocated on the heap. To allocate heap memory you use new (in C++) or malloc (in C).

2. When you allocate memory for a string, you always need one more extra byte for the null termination.

In your case, you should have done:

secondValue = new char[strlen(value)+1];

Other than that, you are correct

Answer 2

If you are using C++ you are correct, except that you need to make secondValue one character bigger:

secondValue = new char[strlen(value) + 1];

C-style strings are terminated with a '\0' character, which also need space to be stored.

If you are using C instead of C++, there is no new or delete[] and you have to use the functions malloc() and free() instead:

secondValue = malloc(strlen(value) + 1);
...
free(secondValue);

In any case note that in the example value is a string literal, which cannot be deleted/freed. You should only delete/free what you allocated with new/malloc respectively.

Answer 3

The way you wrote your code:

char* value = "abcdefg";

The compiler will generate a static string "abcdefg", and value will be a pointer to that. You may assign secondvalue = value and then have value go out of scope, andsecondvalue` will still be valid.

In your example there is no other way to deallocate value.