CODEWITHSUNDEEP
cpointersstruct
TheFaster
TheFaster

Reputation: 241

char* in structs not being free()'d by cleanUp function

I've read that the rule when using malloc() is to always have a matching free(). If malloc() is used 7 times in a program, there must be a corresponding number of free()s. However, this does not seem to be working for several char* I've malloc'd inside of a struct. The struct:

typedef struct
{
    char* ID;
    char* PassWord;
}Account, *pAccount, **ppAccount;

typedef struct
{
    unsigned int numAccounts;
    ppAccount accounts;
}Collection,*pAccountCollection;

The mallocs (function simplified):

void AddNewAccount(pAccountCollection e){
    int string_length = sizeof(char)*26;
    pAccount newAct = malloc(sizeof(Account));

    newAct->ID = malloc(string_length);
    newAct->PassWord = malloc(string_length);
    e ->numAccounts++;

    e->accounts[e->numAccounts-1] = newAct;
}

And finally, the cleanup called at the end:

void CleanUp(pAccountCollection e){
unsigned int i;

    if(e->numAccounts != 0){
        for (i = 0; i < e->numAccounts; i++){
            free(e->accounts[i]->ID);
            free(e->accounts[i]->PassWord);
            free(e->accounts[i]);
        }
        free(e->accounts);
    }
}

I'm checking for leaks with 

    _CrtDumpMemoryLeaks();
    _CrtSetDbgFlag(_CRTDBG_ALLOC_MEM_DF|_CRTDBG_LEAK_CHECK_DF);

And it's flagging the ID and PassWord of newAct as 26 bytes not being freed. 

 Detected memory leaks!
 Dumping objects ->
 {73} normal block at 0x006F9268, 26 bytes long.
   Data: <                > CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD 
 {72} normal block at 0x006F45E8, 26 bytes long.
   Data: <                > CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD

If I free them at the end of the fuction like so:

void AddNewAccount(pAccountCollection e){
    int string_length = sizeof(char)*26;
    pAccount newAct = malloc(sizeof(Account));

    newAct->ID = malloc(string_length);
    newAct->PassWord = malloc(string_length);

    e->accounts[e->numAccounts-1] = newAct;
    free(newAct->ID);
    free(newAct->PassWord);
}

I lose the reference to that account in the collection of accounts AccountCollection e.

Any insight?

Upvotes: 1

Views: 117

Answers (1)

Mankarse
Mankarse

Reputation: 40623

Your AddNewAccount function never increments e->numAccounts, and so CleanUp always acts as though the Collection contains no accounts, and so does nothing.

Upvotes: 5

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