c - 如何有效地添加 2 个不同大小的链表

Question

我在将两个不同大小的链表相加时遇到问题。他们已经逆转了。其他一切似乎都有效，但我知道问题出在 while 循环中

 while(num1 != NULL && num2 != NULL)

当我使用 && 运算符时，它只会停止到第一个完成列表的末尾(我明白这一点)。但是，当我尝试使用 or (||) 运算符时，我的整个程序都崩溃了。请有人帮我找出问题所在。

这是函数。和我的主要。

//adds the two linked lists for their sum
node *addLargeNumber(node *num1, node *num2) {
    node *result = NULL;
    node *prev = NULL;
    node *temp;
    int sum, carry = 0;

    while(num1 != NULL || num2 != NULL) { //while both lists exists or either is not empty
        /*calculate values for the result. the next digit with be the sum of the carry
        from previous number(if any) digit from 1st list and digit from second list*/

        sum = carry + (num1->data) + (num2->data);                   
        if (sum > 9) carry = 1;
            else carry = 0;
        sum = sum % 10; //just want ones column from sum to put in result      
        temp = createNode(sum);

        if(result == NULL) 
            result = temp; //if it is first node, make it the head  
        else 
            prev->next = temp; //if not first node, connect it to rest
        prev = temp; //reset prev or next insertion

        // move to next nodes in both lists
        if(num1 != NULL) num1 = num1->next;
        if(num2 != NULL) num2 = num2->next;
    }

      if(carry > 0) temp->next = createNode(carry);        
      return result;
}

主要功能

int main(void) {
    node *storeNumber();
    void reverseList();
    void printList();
    node *addLargeNumber();
    node *add();

    char number1[numsize], number2[numsize], bigSum[numsize];
    node *top;
    char command;
    int number;

    FILE *in = fopen("input.txt", "r");
    FILE *out = fopen("output.txt", "w");

    while(fscanf(in, "%c", &command) != EOF) {   //while there are no more commands to be read
        top = NULL;  
        //adding two large numbers with linked list
        if(command == 'A') {
            fscanf(in, "%s", &number1);
            fscanf(in, "%s", &number2);   
            node *top1 = storeNumber(number1);
            node *top2 = storeNumber(number2);
            node *sum = addLargeNumber(top1, top2);

            printList(top1);
            printf("  +  ");
            printList(top2);
            printf("  =  ");
            printList(sum);
            printf("\n\n");
            fscanf(in, "%c", &command); 
        }
    }
    system("Pause");
    return 0;   
}

Answer 1

如果你使用 || “或”运算符，num 之一可能为 null，当您尝试访问 num1->data 时程序崩溃或 num2->data

尝试类似的东西:

 sum = carry;
 if(num1 != NULL) sum += num1->data;
 if(num2 != NULL) sum += num2->data;

和

 if(num1!= NULL) num1 = num1->next;
 if(num2!= NULL) num2 = num2->next;