CODEWITHSUNDEEP
c++
CLearner
CLearner

Reputation: 542

C++ Proper way of deleting a new struct array that contains new struct array?

What is the proper way of deleting a new struct array that contains new struct array?

typedef struct CALF_STRUCTURE
{
    char* Name;
    bool IsBullCalf;
} CALF;

typedef struct COW_STRUCTURE
{
    CALF* Calves;
} COW;

int main( void )
{
    COW* Cows;
    Cows = new COW[ 3 ];                // There are 3 cows.

    Cows[ 0 ].Calves = new CALF[ 2 ];   // The 1st cow has 2 calves.
    Cows[ 1 ].Calves = new CALF[ 1 ];   // The 2nd cow has only 1 calf.
    Cows[ 2 ].Calves = new CALF[ 25 ];  // The 3rd cow has 25 calves. Holy cow!

    Cows[ 2 ].Calves[ 0 ].Name = "Bob"; // The 3rd cow's 1st calf name is Bob.

    // Do more stuff...

Now, its time do clean-up! But...what is the proper way of deleting the cows and calves array or any type of struct array?

Should I delete all of the cows's calves array in a for-loop first? Like this:

// First, delete all calf struct array (cows[x].calves)
for( ::UINT CowIndex = 0; CowIndex != 3; CowIndex ++ )
    delete [ ] Cows[ CowIndex ].Calves;

// Lastly, delete the cow struct array (cows)
delete [ ] Cows;

return 0;
};

Or should I just simply delete the cows array and hope that it will also delete all calves array? Like this:

// Done, lets clean-up
delete [ ] Cows;

return 0;
};

Or?

Upvotes: 0

Views: 306

Answers (2)

Luchian Grigore
Luchian Grigore

Reputation: 258558

Neither. To do this in C++:

struct CALF
{
    std::string Name;
    bool IsBullCalf;
};

and

struct COW
{
    std::vector<CALF> Calves;
};

and, in main:

std::vector<COW> Cows(3);

By magic, you no longer need to delete anything.

Upvotes: 1

Jack
Jack

Reputation: 133567

You will have to manually delete nested arrays.

But since you are using C++ forget about arrays and just use std::vector:

typedef struct COW_STRUCTURE
{
    std::vector<CALF> calves;
} COW;

int main( void ) {
  std::vector<COW> cows;

Why don't you want to use something that will manage everything for you in an efficient and moreover safe way?

Just as a side info:

  • type names usually are not all capitalized (eg. Cow or cow but rarely COW), capitalization is for constants
  • variables are usually camel case or lowercase with underscore (so calves not Calves)

Upvotes: 1

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