trie_children (Map)

Gets the items in a trie whose keys start with the specified value.

Syntax

unsigned int trie_children(TrieMap* trie, key_type* key, key_type** keys, unsigned int keys_size, value_type* values, unsigned int values_size, unsigned int max_length, bool allocate_keys);

Returns: If keys or values are not NULL, the number of items added to them. Otherwise, returns the number of keys that start with key and are no longer than max_length.

Remarks

If key is NULL, gets all of the children. Consider using the trie_iter extension.

keys or values can be NULL to only get one or the other.

The key and value at an index in keys and values correlate to the item in the map. For example if keys[0] is "one" and values[0] is 1, the item was added to the trie like so trie_add(trie, "one", 1).

The sizes of keys and values can be different.

If both keys and values are NULL, returns the result of trie_children_count.

If allocate_keys is true, the values in keys will be allocated by the function. In this case, it’s up to the called to free the memory. Otherwise, it’s expected that each item in keys should be big enough to a fit a key as large as max_length + 1 (to null-terminate).

When the function allocates a key, it uses the minimum amount of space necessary to hold the value, so it is more memory efficient, but it the memory has alread been allocated, might as well use the existing space.

Example

TRIE_MAP_DEFINE_H(StringTrie, str_trie, char, int)
TRIE_MAP_DEFINE_C(StringTrie, str_trie, char, int)

StringTrie* trie = str_trie_create();

str_trie_add(trie, "one", 1);
str_trie_add(trie, "two", 2);
str_trie_add(trie, "three", 3);

unsigned int size = 4;
char** keys = malloc(size * sizeof(*keys));
int* values = malloc(size * sizeof(*values));

unsigned int count = str_trie_childre(trie, "t", keys, size, values, size, INT_MAX, true);

printf("Count: %u\n", count);

for(int i = 0; i < count; i++) {
    printf("Key: %s, Value: %d\n", keys[i], values[i]);
}

// Make sure to clean up the memory allocated by the function.

for(int i = 0; i < count; i++) {
    free(keys[i]);
}

str_trie_free(trie);

// Output:
// Count: 2
// Key: two, Value: 2
// Key: three, Value: 3