C 程序中的链表在插入期间终止

Question

struct node
{
    char key;
    struct node *next;
};
typedef struct node *node; 
struct list                 
{
    node head; 
};
typedef struct list *list; 
node CREATE(char k)
{
    
    node tmp;                                
    tmp = (node)malloc(sizeof(struct node)); 
    if (tmp == NULL)  
    {                    
        exit(0);
    }
    tmp->key = k;
    tmp->next = NULL; 
    return temp;      
}

void InsertAtBeg(list L, char k) //insert at the beginning
{
    
    node x;
    x = CREATE(k); //creating a node

    x->next = L->head; //inserting at the beginning
    L->head = x;
    
}

This is the main function

int main()
{
list L;
    char k;
    char x, y;
    char ch = 'q';
while(ch!='e') //termination condition
{
           
            scanf("%c ",&ch);
            switch(ch)
            {
                            case 'i': //first case
                            scanf("%c",&k);
                           
                            
                            InsertAtBeg(L,k);
                            
                            break;
                            .............//more options are below but none of them work including first
}
}
}

Once I input the two characters-choice and the key for the new node, the program breaks the loop even though I have not given the termination character -'e'; Is it a problem with linked list implementation or with scanf function?

I think code works now. It was required to initialize L->head as null before the creation of the linked list.

Answer 1

删除多余的空白 scanf("%c",&ch);