libdice

libdice is a small C library for rolling P&P style dice and for evaluating dice expressions.

Features

• Written in ANSI C99
• Uses solid and reliable RNG, no need for seeding
• Mathematic expression library for advanced dice rolling

Dice syntax

Currently the supported syntax in libdice is rather limited. It only supports variable amount, variable sides and fudge dice at the moment:

• Roll four six sided dices: 4d6
• Roll one twenty sided die: d20
• Roll six fudge dice: 6dF

Build

libdice requires:

• libbsd (on systems without a native arc4random_uniform)
• bison
• flex
• cmocka >= 1.0.1
• cmake

To build libdice run:

$ mkdir build; cd build
$ cmake .. -DCMAKE_INSTALL_PREFIX=/usr
$ make
$ make test
$ sudo make install

Dice API

The core api relies on dice_new which creates a new dice (or a set of dice), which is then freed by dice_free. Dice can be initialised through the proper dice_set function, or by using either dice_simple or dice_parse:

#include <dice.h>

dice_t d = dice_new();

dice_set(d, DICEOPTION_AMOUNT, 4);
dice_set(d, DICEOPTION_SIDES, 6);

/* or simpler:
 * d = dice_simple(4, 6);
 */


printf("%ld\n", dice_roll(d));
dice_free(d);

There is also an easier API:

dice_t d20 = dice_simple(1, 20);

printf("%ld\n", dice_roll(d20));
dice_free(d20);

And a more advanced API:

dice_t d = dice_simple(4, 6);
dice_result_t *res = NULL;
size_t reslen = 0, i = 0;

if (!dice_evaluate(d, &res, &reslen)) {
    goto fail;
}

for (; i < reslen; i++) {
    printf("%ld\n", res[i].result);
}

fail:
dice_result_freev(res, reslen);
dice_free(d);

You can also parse dice strings:

dice_t d20 = dice_new();

if (!dice_parse(d20, "5d20")) {
   char const *err = NULL;
   dice_get(d20, DICEOPTION_ERROR, &err);
   fprintf(stderr, "error: %s\n", err);
}

printf("%ld\n", dice_roll(d20));
dice_free(d20);

Expression API

The expression API supports multiple die within one mathematical expression. Expressions are parsed using tinyexpr library. The API works with objects of the type dice_expression_t, which are allocated using dice_expression_new, and must be freed by using dice_expression_free. Expressions in the format of a C string, can be parsed by using dice_expression_parse, and a result can be evaluated by using dice_expression_roll.

int error = 0;
char const *expr = "1d20+8+4+3-1";
dice_expression_t e = dice_expression_new();
int64_t result = 0;

if (!dice_expression_parse(e, expr, &err)) {
    fprintf(stderr, "error in expression: \"%s\": at %d\n", expr, err);
    goto fail;
}

if (!dice_expression_roll(e, &result)) {
    goto fail;
}

printf("%ld\n", result);

fail:
dice_expression_free(e);

Copyright

libdice is dual licenced. The tinyexpr is licenced under the zlib licence (see LICENSE.tinyexpr), and the rest of libdice is available under the LGPLv3.

tinyexpr Copyright (C) 2015, 2016 Lewis Van Winkle

libdice Copyright (C) 2018 Florian Stinglmayr