C Program: Print Linked List from Recursive Ordering Function

问题

I am creating a linked list by reading in a text file and inserting the letters in alphabetical order in the list. I need to print the list, but cannot seem to get the correct function. I keep getting an error

error: invalid type argument of ‘->’ (have ‘order_list’)
error: invalid type argument of ‘->’ (have ‘order_list’)

I know this is incorrect, but I am at a loss for correctly stating the print_alph function. Any help in finding a way to correctly print my list would be greatly appreciated.

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

typedef struct list_node_alph {
    int key;
    struct list_node_alph *rest_old;
} list_node_order; 

typedef struct {
    list_node_order *the_head;
    int size;
} order_list;

list_node_order *rec_alph_order(list_node_order * old_list, int new_key);
void insert_node(order_list *the_alph, int key);
void print_alph(order_list my_list);

list_node_order *rec_alph_order(list_node_order *old_list, int new_key) {
    list_node_order *new_list;

    if (old_list == NULL) {
            new_list = (list_node_order *)malloc(sizeof (list_node_order));
            new_list->key = new_key;
            new_list->rest_old = NULL;
    } else if (old_list->key >= new_key) {
            new_list = (list_node_order *)malloc(sizeof (list_node_order));
            new_list->key = new_key;
            new_list->rest_old = old_list;
    } else {
            new_list = old_list;
            new_list->rest_old = rec_alph_order(old_list->rest_old, new_key$
    }
    return (new_list);
}

void insert_node(order_list * the_alph, int key) {
    ++(the_alph->size);
    the_alph->the_head = rec_alph_order(the_alph->the_head, key);
}

void print_alph(order_list my_list) {
    printf("Pangram in alphabetical order: ");
    while(my_list->head != NULL) {    //ERROR
            printf("%c", my_list->the_head);    //ERROR
    }
}

int main(void) {
    int ch_count;
    int count_pangram;
    char *pang_arr;
    FILE *alph_text;

    alph_text = fopen("pangram.txt", "r");
    if (alph_text == NULL) {
            printf("Empty file. \n");
    }
    order_list my_alph = {NULL, 0};
    while (( ch_count = fgetc(alph_text)) != EOF) {
            putchar(ch_count);
            char next_key;
            int the_count;

            for (the_count = 0; the_count < 100; the_count++) {
                    if (fscanf(alph_text, "%c", &next_key) != ' ') {
                    //order_list my_alph = {NULL, 0};
                    //for(next_key; next_key != SENT; scanf("&c", &next_key$
                    insert_node(&my_alph, next_key);
                    }
            }
    }
    print_alph(my_alph);
    fclose(alph_text);
    return(0);
}

回答1:

Here in print_alph() you are passing instance of type order_list so to access its member you should use . not ->

so change

  while(my_list->head != NULL){

  while(my_list.the_head != NULL){

But i think instead of passing its instance you should pass pointer of that object in print_alph() In that case -> is fine to access its member.

void print_alph(order_list *my_list)

and call it as

print_alph(&my_alph);

回答2:

You need to use . instead of -> inside print_alph function as you have not passed order_list as pointer

void print_alph(order_list my_list){
    printf("Pangram in alphabetical order: ");
    while(my_list.head != NULL){
            printf("%c", my_list.the_head);
    }
}

来源：https://stackoverflow.com/questions/23003948/c-program-print-linked-list-from-recursive-ordering-function

标签

recursion

linked-list