Data structures are key knowledge points in C language interviews: pointers and arrays: Understand pointers point to the array start address and are used to access and modify array elements. Linked List: Implement a one-way linked list to master the creation, insertion and deletion operations. Stack: Use arrays to build a stack, understand stack pressing, stacking and viewing stack top operations. Queue: Use arrays to implement queues to master the operations of joining, dequeuing and viewing team heads.

C Language Data Structure: Analysis of Common Interview Questions

In many programming interviews, data structures are inevitable topics. Mastering common data structures and their applications in C is crucial for job seekers.

1. Pointer and array

• Understand the principle of pointers pointing to the starting address of an array.

   int arr[] = {1, 2, 3, 4, 5};
  int *ptr = arr; // Point to the first element of the array

• Use pointers to access and modify array elements.

   printf("%d\n", *ptr); // Output 1
  *ptr ; // Point to the next array element printf("%d\n", *ptr); // Output 2

2. Link list

• Implement unidirectional linked lists and their basic operations (create, insert, delete).

   struct node {
    int data;
    struct node *next;
  };
  
  struct node *head = NULL; // header of linked list// create linked list void create_list(int data) {
    struct node *new_node = malloc(sizeof(struct node));
    new_node->data = data;
    new_node->next = NULL;
  
    if (head == NULL) {
        head = new_node;
    } else {
        struct node *current = head;
        while (current->next != NULL) {
            current = current->next;
        }
        current->next = new_node;
    }
  }
  
  // Insert node to specific location of the linked list void insert_node(int data, int position) {
    struct node *new_node = malloc(sizeof(struct node));
    new_node->data = data;
  
    if (position == 0) {
        new_node->next = head;
        head = new_node;
    } else {
        struct node *current = head;
        for (int i = 0; i < position - 1 && current != NULL; i ) {
            current = current->next;
        }
  
        if (current != NULL) {
            new_node->next = current->next;
            current->next = new_node;
        }
    }
  }
  
  // Delete node void delete_node(int position) {
    struct node *current = head;
  
    if (position == 0) {
        head = head->next;
    } else {
        for (int i = 0; i < position - 1 && current != NULL; i ) {
            current = current->next;
        }
  
        if (current != NULL && current->next != NULL) {
            struct node *temp = current->next;
            current->next = temp->next;
            free(temp);
        }
    }
  }

3. Stack

• Implement the stack and use array simulation to understand the basic operations of the stack (press the stack, out the stack, view the top of the stack).

   #define MAX_SIZE 100
  
  int stack[MAX_SIZE];
  int top = -1; // top pointer// stack push(int data) {
    if (top == MAX_SIZE - 1) {
        printf("Stack overflow\n");
    } else {
        stack[top] = data;
    }
  }
  
  // Int pop() {
    if (top == -1) {
        printf("Stack underflow\n");
        return -1;
    } else {
        return stack[top--];
    }
  }
  
  // View the top element of the stack int peek() {
    if (top == -1) {
        printf("Empty stack\n");
        return -1;
    } else {
        return stack[top];
    }
  }

4. Queue

• Use arrays to implement queues to understand the basic operations of queues (enter, dequeue, and view the team leader).

   #define MAX_SIZE 100
  
  int queue[MAX_SIZE];
  int front = -1, rear = -1;
  
  // Enlist void enqueue(int data) {
    if ((front == 0 && rear == MAX_SIZE - 1) || (rear 1 == front)) {
        printf("Queue overflow\n");
    } else if (front == -1) {
        front = rear = 0;
        queue[rear] = data;
    } else if (rear == MAX_SIZE - 1) {
        rear = 0;
        queue[rear] = data;
    } else {
        rear ;
        queue[rear] = data;
    }
  }
  
  // Dequeue int dequeue() {
    if (front == -1) {
        printf("Queue underflow\n");
        return -1;
    } else if (front == rear) {
        int data = queue[front];
        front = rear = -1;
        return data;
    } else {
        int data = queue[front];
        front ;
        return data;
    }
  }
  
  // View the team's head element int peek() {
    if (front == -1) {
        printf("Queue empty\n");
        return -1;
    } else {
        return queue[front];
    }
  }

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