feat: add a vector implementation in data structures (#977)

* added a vector implementation in data structures

* changed a comment

* made the required changes

* added tests

data_structures/vector.c

@@ -0,0 +1,168 @@
+/**
+ * @file
+ * @brief This is a vector implemenation in C. A vector is an expandable array.
+ * @details This vector implementation in C comes with some wrapper functions that lets the user work with data without having to worrying about memory.
+ */
+
+#include <stdio.h>     /// for IO operations
+#include <stdlib.h>    /// for malloc() and free()
+#include <assert.h>    /// for testing using assert()
+
+/** This is the struct that defines the vector. */
+typedef struct {
+    int len;           ///< contains the length of the vector
+    int current;       ///< holds the current item
+    int* contents;     ///< the internal array itself
+} Vector;
+
+/**
+ * This function initilaizes the vector and gives it a size of 1
+ * and initializes the first index to 0.
+ * @params Vector* (a pointer to the Vector struct)
+ * @params int     (the actual data to be passed to the vector)
+ * @returns none
+ */
+void init(Vector* vec, int val) {
+    vec->contents = (int*)malloc(sizeof(int));
+    vec->contents[0] = val;
+    vec->current = 0;
+    vec->len = 1;
+}
+
+/**
+ * This function clears the heap memory allocated by the Vector.
+ * @params Vector* (a pointer to the Vector struct)
+ * @returns: none
+ */
+void delete(Vector* vec) {
+    free(vec->contents);    
+}
+
+/**
+ * This function clears the contents of the Vector.
+ * @params Vector* (a pointer to the Vector struct)
+ * @returns: none
+ */
+void clear(Vector* vec) {
+    delete(vec);
+    init(vec, 0);
+}
+
+/**
+ * This function returns the length the Vector.
+ * @params Vector* (a pointer to the Vector struct)
+ * @returns: int
+ */
+int len(Vector* vec) {
+    return vec->len;    
+}
+
+/**
+ * This function pushes a value to the end of the Vector.
+ * @params Vector* (a pointer to the Vector struct)
+ * @params int     (the value to be pushed)
+ * @returns: none
+ */
+void push(Vector* vec, int val) {
+    vec->contents = realloc(vec->contents, (sizeof(int) * (vec->len + 1)));
+    vec->contents[vec->len] = val;
+    vec->len++;
+}
+
+/**
+ * This function get the item at the specified index of the Vector.
+ * @params Vector* (a pointer to the Vector struct)
+ * @params int     (the index to get value from)
+ * @returns: int
+ */
+int get(Vector* vec, int index) {
+    if(index < vec->len) {
+        return vec->contents[index];
+    }
+    return -1;
+}
+
+/**
+ * This function sets an item at the specified index of the Vector.
+ * @params Vector* (a pointer to the Vector struct)
+ * @params int     (the index to set value at)
+ * @returns: none
+ */
+void set(Vector* vec, int index, int val) {
+    if(index < vec->len) {
+        vec->contents[index] = val;
+    }
+}
+
+/**
+ * This function gets the next item from the Vector each time it's called.
+ * @params Vector* (a pointer to the Vector struct)
+ * @returns: int
+ */
+int next(Vector* vec) {
+    if(vec->current == vec->len) {
+        vec->current = 0;
+    }
+    int current_val = vec->contents[vec->current];
+    vec->current++;
+    return current_val;
+}
+
+/**
+ * This function returns the pointer to the begining of the Vector.
+ * @params Vector* (a pointer to the Vector struct)
+ * @returns: void*
+ */
+void* begin(Vector* vec) {
+    return (void*)vec->contents;
+}
+
+/**
+ * This function prints the entire Vector as a list. 
+ * @params Vector* (a pointer to the Vector struct)
+ * @returns: none
+ */
+void print(Vector* vec) {
+    int size = vec->len;
+    printf("[ ");
+    for(int count = 0; count < size; count++) {
+        printf("%d ", vec->contents[count]);
+    }
+    printf("]\n");
+}
+
+/**
+ * This function tests the functions used to work with Vectors.
+ * @returns: none
+ */
+static void test() {
+    Vector vec;
+    init(&vec, 10);
+    assert(get(&vec, 0) == 10);
+    push(&vec, 20);
+    assert(get(&vec, 1) == 20);
+    set(&vec, 0, 11);
+    assert(get(&vec, 0) == 11);
+    assert(next(&vec) == 11);
+    set(&vec, 1, 22);
+    assert(get(&vec, 1) == 22);
+    assert(len(&vec) == 2);
+}
+
+/**
+ * @brief Main function
+ * @returns 0 on exit
+ */
+int main() {
+    test();
+
+    Vector vec;
+    init(&vec, 10);
+    push(&vec, 20);
+    print(&vec);
+    set(&vec, 0, 11);
+    set(&vec, 1, 22);
+    print(&vec);
+    printf("Length: %d\n", len(&vec));
+    return 0;
+}