Python-like dictionary datatype written in C

Dictionary is a key-value storage useful for different purposes.

The key is always of type char * (string) and the value can be any type.

Since we don't know the type of the value in advance, (it can be a pointer to char or int or a custom structure), We have to know how to copy the value and how to free the allocated memory for the value.

Therefore, the cdict_init() function will accept two parameters:

1. cdict_free_func: A pointer to the user provided function to free the memory for the value.
2. cdict_copy_func: A pointer to the user provided function to copy the value.

Other things are easy to use and understand.

There are currently four functions available for the dictionary structure:

1. Adding a key-value pair to the dictionary
2. Removing a key-value pair from a dictionary
3. Getting a value from the dictionary by providing the key
4. Lists all the keys

Example

Check the examples in test directory.

Here is a small example:

Compile this with:

# inside the test directory
gcc -O2 ./test_1.c ../src/cdict.c ../include/cdict.h -o test
 
# and then run ./test

#include <cdict.h>
#include <cunittest.h>
#include <stdlib.h>
 
void dict_free_func(void * value){
    free(value);
}
 
void* dict_copy_func(void * value){
    return (void*) strdup((char*)value);
}
 
int main(int argc, char ** argv){
    // this is only used to create random keys and values
    srand(1);
 
    ABORT_ON_FAIL(1);
 
    // creating a new context
    cdict_ctx* new_dict = NULL;
 
    // number of key-values to insert
    int COUNT = 500000;
 
    // we store strings as values in the dictionary. So the standard 'free()'
    // function and 'strdup()' for copying and freeing operations are enough.
 
    // creating a context with free and strdup functions as params.
    new_dict = cdict_init(free, (void*)strdup);
 
    // add random key, values to the dictionary
    int random_val = 0;
    char key[50] = {0};
    for (int i=0; i< COUNT; ++i){
        random_val = rand();
        sprintf(key, "key_%d", random_val);
        // before insertion check if the key exists
        if (cdict_has_key(new_dict, key)){
            fprintf(stdout, "We already have this key: %s\n", key);
            continue;
        }
        cdict_set(new_dict, key, (void *)"John Doe");
    }
    cdict_keylist * klst = NULL;
    klst = cdict_keys(new_dict, 0);
    fprintf(stdout, "We have %d keys\n", klst->len);
    for (unsigned long int i=0; i< klst->len; ++i){
        //fprintf(stdout, "%s -> %s\n", klst->lst[i], (char*)cdict_get(new_dict, klst->lst[i]));
    }
    cdict_free_keylist(klst, 0);
    cdict_free(new_dict);
    return 0;
}

1. test_1.c: shows how to insert key-value pairs to the dictionary and check if a key exists.

if values are of type char *, then I use

cdict_ctx * dict = cdict_init(free, (char*) strdup);

to initialize the dictionary.

However, if I want to store a custom structure in the dictionary, I have to provide two custom functions to free and copy the structure for me.

Look at test_2.c in the test directory for more info.

1. test_remove.c in test directory shows how to remove the key in a for-loop.
2. test_2.c in test directory shows how to store custom structure as values in the dictionary.

Documentation

Use Doxygen to generate the documents