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Dynamic Arrays

Table of contents

initialize_list

The function should be called to create a list and returns its head-pointer. If an error occurs, the function will return a NULL-Pointer.

Usage & Example

int numbber = 1337;

DynamicArray* head_ptr = initialize_list((void*)&number, sizeof(number));

if (head_ptr == NULL) {
    return 1;
}

// Deallocate DynamicArray
clear_list(head_ptr);

dynamic_array_from_elements

This function copies the actual values of the given static-array.

Usage & Example

int numbers[] = {1,2,3,4,5};

size_t element_size = sizeof(int);

DynamicArray* head_ptr = dynamic_array_from_elements(numbers, element_size, sizeof(numbers) / element_size);

if (head_ptr == NULL) {
    return 1;
}

for (int i = 0; i < 5; i++) {
    printf("(i=%d) ELEMENT=%d\n",i,*(int*)get_element_by_index(head_ptr,i));
}

numbers[0] = 9;

for (int i = 0; i < 5; i++) {
    printf("(i=%d) ELEMENT=%d\n",i,*(int*)get_element_by_index(head_ptr,i));
}

// Deallocate DynamicArray
clear_list(head_ptr);

The output would be:

(i=0) ELEMENT=1
(i=1) ELEMENT=2
(i=2) ELEMENT=3
(i=3) ELEMENT=4
(i=4) ELEMENT=5
(i=0) ELEMENT=1
(i=1) ELEMENT=2
(i=2) ELEMENT=3
(i=3) ELEMENT=4
(i=4) ELEMENT=5

While the static-array has been modified, the values in the dynamic-list remain unmodified.

dynamic_array_from_whole

This function copies the the pointers to its elements and saves them into a dynamic-array.

Usage & Example

int numbers[] = {1,2,3,4,5};

size_t element_size = sizeof(int);

DynamicArray* head_ptr = dynamic_array_from_whole(numbers, element_size, sizeof(numbers) / element_size);

if (head_ptr == NULL) {
    return 1;
}

Printing out its content:

for (int i = 0; i < 5; i++) {
    int* this_elements = (int*)head_ptr->element;
    printf("(i=%d) ELEMENT=%d\n",i,this_elements[i]);
}

The output would be:

(i=0) ELEMENT=1
(i=1) ELEMENT=2
(i=2) ELEMENT=3
(i=3) ELEMENT=4
(i=4) ELEMENT=5

But when an element is modified in the static-array, it also will be modified „in the dynamic-array”. This happens, because dynamic_array_from_whole just saves the reference (the pointer) to the actual values and not their data.

numbers[0] = 9;

The new output would be:

(i=0) ELEMENT=9
(i=1) ELEMENT=2
(i=2) ELEMENT=3
(i=3) ELEMENT=4
(i=4) ELEMENT=5

And of course, don't forget to clear the allocated data:

clear_list(head_ptr);