链表逻辑错误导致程序冻结

Question

我正在尝试创建 classic 贪吃蛇游戏（在 Linux 终端中），但我的链表 and/or 基本逻辑实现有问题.我相当确定我的 move_snake() 方法是正确的 - 然而，在 grow_snake() 完成后，添加与检索到的奖杯值相同数量的节点，程序冻结。我有一种感觉，这是因为我如何在 grow_snake() class 中分配我的指针，特别是在添加到蛇头之后，但我一直遇到这样的困难在这一点上，我真的可以使用另一双眼睛。提前致谢。

move_snake()

// Moves the snake based on user input, via key press
void move_snake(){
    struct snake_struct *temp_ptr = root;
    struct snake_struct *last_node = malloc(sizeof(struct snake_struct *));
    change_direction(ui);                                   // Change direction on UI
    draw_border();                                          // Clear screen & draw border
    draw_trophy();                                          // Keep trophy on screen

//    grow_snake();
    check_position();

    while(temp_ptr->next){
        mvaddch(temp_ptr->y_pos, temp_ptr->x_pos, DEFAULT_SYMBOL);
        last_node = temp_ptr;
        temp_ptr = temp_ptr->next;
    }

    temp_ptr->x_pos = root->x_pos + x_dir;
    temp_ptr->y_pos = root->y_pos + y_dir;
    if(root->next != NULL)
        temp_ptr->next = root;
    last_node->next = NULL;
    root = temp_ptr;


    mvaddch(root->y_pos, root->x_pos, set_symbol());
    refresh();
    usleep(speed);
}

grow_snake()

// Grows the snake based on trophy value that was ate
void grow_snake(){

struct snake_struct *temp_ptr = root;
struct snake_struct *new_head = malloc(sizeof(struct snake_struct *));
change_direction(ui);                                   // Change direction on UI
//    int num_links = 2;
int num_links = trophy.value;
generate_trophy();
int i = 0;
draw_border();                                          // Clear screen & draw border
draw_trophy();                                          // Keep trophy on screen

    while(temp_ptr->next){
        mvaddch(temp_ptr->y_pos, temp_ptr->x_pos, DEFAULT_SYMBOL);
        temp_ptr = temp_ptr->next;
    }

for(i = 0; i < num_links; i++) {
    new_head->x_pos = root->x_pos + x_dir;
    new_head->y_pos = root->y_pos + y_dir;
    new_head->next = root;
    new_head->symbol = DEFAULT_SYMBOL;
    root = new_head;
    set_symbol();
    change_direction(ui);
    mvaddch(root->y_pos, root->x_pos, root->symbol);
    refresh();
    usleep(speed);
    }
}

change_direction()

// Changes direction on user key input
void change_direction(char key_press){
    if ((char) tolower(key_press) == 'w'){
        if(y_dir == 1 && root->next){
            alert(2);
        }
        else{
            y_dir = -1;
            x_dir = 0;
        }
    }
    else if ((char) tolower(key_press) == 'a'){
        if(x_dir == 1 && root->next){
            alert(2);
        }
        else{
            y_dir = 0;
            x_dir = -1;
        }
    }
    else if ((char) tolower(key_press) == 's'){
        if(y_dir == -1 && root->next){
            alert(2);
        }
        else{
            y_dir = 1;
            x_dir = 0;
        }
    }
    else if ((char) tolower(key_press) == 'd'){
        if(x_dir == -1 && root->next){
            alert(2);
        }
        else{
            y_dir = 0;
            x_dir = 1;
        }
    }
}

Answer 1

我的感觉是，您必须在 grow_snake 的每次迭代中创建一个 new_head。例如移动

struct snake_struct *new_head = malloc(sizeof(struct snake_struct *));

直接在

之后

for(i = 0; i < num_links; i++) {

Answer 2

在 grow_snake() 函数中，您的 malloc() 调用没有分配正确数量的字节。通过写作：

malloc(sizeof(struct snake_struct *));

您分配的是指向您的结构的指针的大小，而不是分配结构本身的大小。删除“*”并尝试

malloc(sizeof(struct snake_struct));

链表逻辑错误导致程序冻结

Linked-list logical errors causes program to freeze

c

debugging

pointers

runtime-error

linked-list