如何在C編程中使用雙向鏈接列表接受字符串？

Question

在這裏，我已經做出了結構DLL： -

struct node 
{ 
    char letter; 
    struct node* prev; 
    struct node* next; 
}; 

，這是接受字符串的函數： -

struct node* accept(struct node* head) 
{ 
    int i=0; 
    char dummy, ch; 
    struct node* memory, *memory1; 
    memory = (struct node*)malloc(sizeof(struct node)); 
    printf("\n Enter the letters "); 
    scanf("%c",&dummy); 
    ch = getchar(); 
    if(ch == '\n') 
    { 
     return head; 
    } 
    memory->letter = ch; 
    memory->prev = NULL; 
    memory->next = NULL; 
    head = memory; 
    while(ch!='\n') 
    { 
     ch = getchar(); 
     memory1 = (struct node*)malloc(sizeof(struct node)); 
     memory1->letter = ch; 
     memory1->prev = memory; 
     memory1->next = NULL; 
     memory = memory1; 
     i++; 
    } 
    n = i; 
    return head; 
} 

及以下的幾乎一半完成的程序： -

#include<stdio.h> 
#include<stdlib.h> 

struct node 
{ 
    char letter; 
    struct node* prev; 
    struct node* next; 
}; 

int n= 0; 

struct node* accept(struct node* head) 
{ 
    int i=0; 
    char dummy, ch; 
    struct node* memory, *memory1; 
    memory = (struct node*)malloc(sizeof(struct node)); 
    printf("\n Enter the letters "); 
    scanf("%c",&dummy); 
    ch = getchar(); 
    if(ch == '\n') 
    { 
     return head; 
    } 
    memory->letter = ch; 
    memory->prev = NULL; 
    memory->next = NULL; 
    head = memory; 
    while(ch!='\n') 
    { 
     ch = getchar(); 
     memory1 = (struct node*)malloc(sizeof(char)); 
     memory1->letter = ch; 
     memory1->prev = memory; 
     memory1->next = NULL; 
     memory = memory1; 
     i++; 
    } 
    n = i; 
    return head; 
} 

void display(struct node* head) 
{ 
    if(head == NULL) 
    { 
     printf("\n Nothing to display .. "); 
     return ; 
    } 
    struct node* temp; 
    temp = head; 
    printf("\n"); 
    while(temp!=NULL) 
    { 
     printf("%c",temp->letter); 
     temp = temp->next; 
    } 
    printf("\n"); 
} 

void reverseDisplay(struct node* head) 
{ 
    struct node* temp; 
    temp = head; 
    while(temp!= NULL) 
    { 
     reverseDisplay(temp->next); 
    } 
    printf("%c",temp->letter); 
} 

struct node* insertChar(struct node* head) 
{ 
    int pos, i; 
    char ch; 
    struct node* temp, *temp1; 
    temp1 = head; 
    printf("\n Enter the position where you want to insert a letter : "); 
    scanf("%d",&pos); 
    if(pos <1 && pos >(n+1)) 
    { 
     printf("\n INVALID POSITION .. "); 
    } 
    else 
    { 
     temp = (struct node*)malloc(sizeof(char)); 
     ch = getchar(); 
     temp->letter = ch; 
     if(ch == '\n') 
     { 
      return head; 
     } 
     if(head == NULL) 
     { 
      temp->next = NULL; 
      temp->prev = NULL; 
      head = temp; 
      return head; 
     } 
     for(i=1; i<pos-1; i++) 
     { 
      temp1 = temp1->next; 
     } 
     temp->next = temp1->next; 
     temp1->next = temp; 
     temp->prev = temp1; 
     temp1->next->prev = temp; 
     n++; 

    } 
    return head; 

} 

int main() 
{ 
    struct node* head; 
    head = NULL; 
    int i,ch; 
    char c; 
    do 
    { 
    printf("\n Enter your choice :\n"); 
    printf("\n 1. Accept the string : "); 
    printf("\n 2. Display the string : "); 
    printf("\n 3. Reverse Display : "); 
    printf("\n 4. Insert a character : "); 
    printf("\n 5. Delete a character : "); 
    printf("\n 6. Modify a character : "); 
    printf("\n 7. Revert the string : "); 
    printf("\n 8. Exit \n : "); 
    scanf("%d",&ch); 

    switch(ch) 
    { 
    case 1: printf("\n Accepting a string ..."); 
      head = accept(head); 
      break; 
    case 2: 
      printf("\n Displaying the string .. "); 
      display(head); 
      break; 
    case 3: 
      printf("\n Reverse Displaying .."); 
      if(head == NULL) 
      { 
       printf("\n There is nothing to be displayed .."); 
       break; 
      } 
      printf("\n"); 
      reverseDisplay(head); 
      break; 
    case 4: 
      head = insertChar(head); 
      break; 


    } 
    }while(ch!=8); 
    return 0; 
} 

問題是，當我選擇顯示文本時，這隻顯示我輸入到字符串中的第一個字母。無法弄清楚。請幫幫我。

幾個輸出實例： -

輸入您的選擇：

1. 接受字符串：
2. 顯示的字符串：
3. 反轉顯示：
4. 插入字符：
5. 刪除一個字符：
6. 修改人物：
7. 還原字符串：

8. 退出 ：1

   接受一個字符串... 輸入字母阿米特upadhyay

   輸入您的選擇：

9. 接受字符串：

10. 顯示字符串：
11. 反轉顯示：
12. 插入一個字符：
13. 刪除字符：
14. 修改字符：
15. 還原字符串：

16. 退出 ：2

    顯示字符串.. 一個

    輸入您的選擇：

17. 接受字符串：

18. 顯示的字符串：
19. 反轉顯示：
20. 插入字符：
21. 刪除字符：
22. 修改字符：
23. 恢復字符串：
24. 退出 ：

Answer 1

你缺少做一個鏈接。

while(ch!='\n') 
{ 
    ch = getchar(); 
    memory1 = (struct node*)malloc(sizeof(struct node)); 
    memory1->letter = ch; 
    memory1->prev = memory; 
    memory1->next = NULL; 

    // The missing link 
    memory->next = memory1; 

    memory = memory1; 
    i++; 
} 

Answer 2

在你malloc是你沒有爲這兩個指針ALLOC足夠的空間，即使用

(struct node*)malloc(sizeof(struct node)); 

，而不是

(struct node*)malloc(sizeof(char)); 

你也忘了初始化memory->next指針，即添加

memory->next = memory1; 

在struct node* accept(struct node* head)的while循環

Answer 3

你是不是問scanf函數的字符串，但對於char

scanf("%c",&dummy); 

應該是：

scanf("%s", &dummy); 

%c = character
%d = decimal (intiger)
%f = flaot
%s = string (character array)

的scanf（）作爲輸入讀取和printf（）作爲打印輸出函數查找上面列出的特殊格式化字符串，然後查找字符串後面的輸入/輸出值。因此，當你有scanf("%d", &value)時，scanf將接受所有輸入作爲十進制值，如果你這樣做scanf("%c", &value) scanf會查找一個字符並在接受一個字符後停止，但如果你把scanf("%s", &value)取回所有字符直到輸入中斷字符爲止通常是\n或者\r或\n\r取決於系統