A deque, shortened from “double-ended queue,” is a versatile data structure in computer science, adept at efficiently adding and removing elements from both ends while also offering indexed access to its elements.
It’s a fundamental tool that plays a significant role in the management of data across various applications. This article will explore how a deque is implemented in C programming language and demonstrate its effective use.
Understanding Deque
Structurally, a deque is akin to a dynamic array comprised of fixed-size arrays. This composition aids in data management efficiency. It operates by filling the first array from right to left and the last array from left to right. Below is a diagram that depicts this concept:
As either end of the array becomes full, a new array is added; conversely, when an array is emptied, it is removed. This dynamic memory allocation enables the deque array to manage data of varying volumes while maintaining high efficiency.
Deque Header File (deque.h)
Here’s an insight into the beginning of a deque’s implementation, starting with a header file that lays down the data structure and offers function prototypes:
#ifndef DEQUE_H
#define DEQUE_H
#include <dynarray.h>
typedef struct {
dynarray *arrays;
unsigned int arraysize;
unsigned int front;
unsigned int back;
unsigned int firstempty;
unsigned int lastempty;
unsigned int count;
} deque;
typedef void (*deque_forfn)(void*);
deque *deque_create(void);
void deque_delete(deque *queue);
void deque_push_front(deque *queue, void *data);
void deque_push_back(deque *queue, void *data);
void *deque_pop_front(deque *queue);
void *deque_pop_back(deque *queue);
void *deque_get_at(const deque *queue, unsigned int index);
void *deque_set_at(deque *queue, unsigned int index, void *data);
void *deque_peek_front(const deque *queue);
void *deque_peek_back(const deque *queue);
void deque_for_each(const deque *queue, deque_forfn fun);
#endif /* DEQUE_H */In this header file, the core data structures, including the deque itself, are defined, and various functions for operating the deque are declared.
Deque Implementation (deque.c)
Next, we will delve into how these functions are realized for the deque in the C language:
#include <stdlib.h>
#include <deque.h>
// Create a new deque
deque *deque_create(void) {
deque *queue = malloc(sizeof(deque));
if (queue) {
queue->arrays = dynarray_create(0);
queue->arraysize = 4;
queue->firstempty = 1;
queue->lastempty = 1;
queue->count = 0;
dynarray_add_head(queue->arrays, malloc(queue->arraysize * sizeof(void*)));
}
return queue;
}
// Delete a deque and its underlying arrays
void deque_delete(deque *queue) {
if (queue) {
dynarray_for_each(queue->arrays, free);
dynarray_delete(queue->arrays);
free(queue);
}
}
// Push an element to the front of the deque
void deque_push_front(deque *queue, void *data) {
// Implementation details...
}
// Push an element to the back of the deque
void deque_push_back(deque *queue, void *data) {
// Implementation details...
}
// Pop an element from the front of the deque
void *deque_pop_front(deque *queue) {
// Implementation details...
}
// Pop an element from the back of the deque
void *deque_pop_back(deque *queue) {
// Implementation details...
}
// Get an element at a specific index in the deque
void *deque_get_at(const deque *queue, unsigned int index) {
// Implementation details...
}
// Set an element at a specific index in the deque
void *deque_set_at(deque *queue, unsigned int index, void *data) {
// Implementation details...
}
// Peek at the element at the front of the deque
void *deque_peek_front(const deque *queue) {
// Implementation details...
}
// Peek at the element at the back of the deque
void *deque_peek_back(const deque *queue) {
// Implementation details...
}
// Perform a function on each element in the deque
void deque_for_each(const deque *queue, deque_forfn fun) {
// Implementation details...
}The execution involves various tasks such as forming and erasing deques, pushing and pulling elements from both ends, offering indexed access to the elements, and iterating over them using a provided function.
Summary
We’ve explored the notion of a deque in C language – a versatile data structure that supports efficient insertion, removal, and indexed access to elements. We’ve also delved into the header file and the intricate details of implementing a deque in C, which can serve as a core structural component for managing data in a myriad of applications.
Deques stand as invaluable tools for adeptly tackling a broad spectrum of tasks. Gaining insights into their implementation in C can offer valuable information to enhance data handling in your individual projects.
By harnessing the capabilities of deques, you can elevate the performance and maintenance convenience of your code, making it more adaptable and capable of conducting complex data operations. Armed with this knowledge, you’ll be well-equipped to integrate deques into your C language projects.