I'm trying to print the elements in the trie (function print_trie), but nothing is displayed in the print statement.

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

#define CHAR_SIZE 26 // Define the character size

struct Trie {
    char data;
    int isLeaf;  // 1 when the node is a leaf node
    struct Trie* character[CHAR_SIZE];
};

struct Trie* getNewTrieNode() {
    struct Trie* node = (struct Trie*)malloc(sizeof (struct Trie));
    node->isLeaf = 0;
    for (int i = 0; i < CHAR_SIZE; i  ) {
        node->character[i] = NULL;
    }
    return node;
}

void insert(struct Trie* head, char* str) {
    struct Trie* curr = head; // start from the root node
    while (*str) {
        // create a new node if the path doesn't exist
        if (curr->character[*str - 'a'] == NULL) {
            curr->character[*str - 'a'] = getNewTrieNode();
        }
        // go to the next node
        curr = curr->character[*str - 'a'];
        // move to the next character
        str  ;
    }

    curr->isLeaf = 1; // mark the current node as a leaf
}

// Here is the code where I'm not able to print the contents of trie
void print_trie( struct Trie* root) {
    if (!root)
        return;
    struct Trie* temp = root;

    for (int i=0; i<CHAR_SIZE; i  ) {
        if(temp->character[i]!='\0')
        printf("%c ",temp->character[i]);
        print_trie(temp->character[i]);
    }
}

int main() {
    struct Trie* head = getNewTrieNode();
    char word[10];
    printf("\nEnter the word to be inserted: ");
    scanf("%s",word);
    insert(head,word);
    printf("Print the nodes in the trie");
    print_trie(head);
    return 0;
}

CodePudding user response：

torstenvl already correctly noted that printf("%c ",temp->character[i]); doesn't work because character[] is an array of pointers. As each element of that array corresponds to a certain lower case character, you can easily retrieve that character:

        printf("%c ", i   'a');

Of course this whole complicated method of storing a string only works as long as the entered string consists of at most nine lower case letters.

CodePudding user response：

struct Trie* character[CHAR_SIZE];

Here character is declared as an array of pointers, not array of characters