How Do I Completely Release Memory Used by a Vector in C ?

C Memory Management: Deleting Objects from Vectors and Arrays

When working with dynamic memory in C , managing the objects and freeing memory can be confusing. This article addresses the misconception of deleting objects in C .

Vector of Objects

Consider the following code snippet:

<code class="cpp">tempObject obj1;
tempObject obj2;
vector<tempObject> tempVector;

tempVector.push_back(obj1);
tempVector.push_back(obj2);</code>

Calling clear() on the vector will destroy the objects stored within it. However, it does not automatically free the allocated memory. To release the memory, a more explicit action is required.

<code class="cpp">vector<tempObject>().swap(tempVector);</code>

Swapping an empty vector with the original effectively deallocates the memory occupied by tempVector.

Vector of Pointers

If tempVector were defined as a vector of pointers to objects instead:

<code class="cpp">vector<tempObject *> *tempVector;
// Push objects...
tempVector->clear();</code>

In this case, clear() deallocates the memory for the objects pointed to by the pointers in the vector, but the pointers themselves still need to be deleted.

Conclusion

While clear() destroys objects within a vector, it does not release the allocated memory. To fully reclaim the memory, explicit actions like swapping with an empty vector or using shrink_to_fit() in C 11 are necessary. It's important to understand these nuances to effectively manage memory in C programs.

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