當我刪除第一個節點時，它會生成一個無限循環錯誤

Question

當我刪除第一個節點時，我的代碼給出了無限循環錯誤，其他的刪除沒問題。

#include <stdio.h> 
#include <stdlib.h> 
struct node //Node 
{ 
    int info; 
    struct node * link; 
}; 
//insertion at begin 
struct node * AddAtBegin(struct node * start, int data) { 
struct node * p; 
p = (struct node *) malloc(sizeof(struct node)); 
p - > info = data; 
p - > link = start; 
start = p; 
return start; 
} 

//insertion at End 
struct node * AddAtEnd(struct node * start, int data) { 
    struct node * p, * q = start; 
    p = (struct node *) malloc(sizeof(struct node)); 
    p - > info = data; 
    p - > link = NULL; 
    while (q - > link != NULL) 
    q = q - > link; 
    q - > link = p; 
    return start; 
} 
//insertion after any given node 
struct node * AddAfter(struct node * start, int data, int node) { 
if (node == ' ') 
    return start; 
struct node * temp, * p = start; 
temp = (struct node *) malloc(sizeof(struct node)); 
temp - > info = data; 
while (p != NULL) { 
    if (p - > info == node) { 
    temp - > link = p - > link; 
    p - > link = temp; 
    return start; 
    } 
    p = p - > link; 
} 
printf("Not Found Your Node"); 
return start; 
} 

//insertion before any given node 
struct node * AddBefore(struct node * start, int data, int node) { 
    if (start == NULL) { 
    printf("List is Empty"); 
    return start; 
    } 
    struct node * p, * q = start; 
    p = (struct node *) malloc(sizeof(struct node)); 
    p - > info = data; 

    if (start - > info == node) { 
    p - > link = start; 
    start = p; 
    return start; 
    } 
    while (q - > link != NULL) { 
    if (q - > link - > info == node) { 
    p - > link = q - > link; 
    q - > link = p; 
    return start; 
    } 
    q = q - > link; 
    } 
    printf("NOT found node"); 
    return start; 
} 
// deletion of node 
int Delete(struct node * start, int data) { 
    struct node * p = start; 
    struct node * temp = NULL; 

    if (start == NULL) { 
    printf("Epty list"); 
    exit(1); 
    } 
    if (p - > info == data) { 
    temp = start; 
    start = p - > link; 
    free(temp); 
    printf("After Deletion of %d == ", data); 
    return 0; 
    } 
    while (p - > link != NULL) { 
    if (p - > link - > info == data) { 
    temp = p - > link; 
    p - > link = temp - > link; 
    free(temp); 
    printf("After Deletion of %d == ", data); 
    return 0; 
    } 
    p = p - > link; 
    } 
    printf("Not Found In The List"); 
    return 0; 
} 
//display of all nodes 
void Display(struct node * start) { 
struct node * p = start; 
while (p != NULL) { 
    printf("%d \t", p - > info); 
    p = p - > link; 
} 
return; 
} 
int main() { 
struct node * start = NULL; 
int i; 
start = AddAtBegin(start, 2); 
start = AddAtBegin(start, 1); 
start = AddAtEnd(start, 4); 
start = AddAtEnd(start, 5); 
start = AddAfter(start, 6, 5); 
start = AddAfter(start, 3, 2); 
start = AddBefore(start, 7, 6); 
start = AddBefore(start, 79, 1); 
printf("List is \n"); 
Display(start); 
printf("\n"); 
scanf("%d", & i); 
Delete(start, i); 
Display(start); 
Delete(start, 7); 
Display(start); 
Delete(start, 79); 
Display(start); 
return 0; 
} 

Answer 1

這是因爲start由值C.變化傳遞給start做主叫方沒有反映。而是傳遞一個指向start的指針。

// deletion of node 
int Delete(struct node ** start, int data) { 
    struct node *p = start; 
    struct node *temp = NULL; 
    if (p - > info == data) { 
    temp = start; 
    *start = p - > link; 
    return 0; 
    } 
    // other cases 
}