General utilities for C
array (style): Move macro line escape to col 80
array: Allow freeing elements of array on free
assert: remove stdbool.h include from header


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#Utility sources for C

This is a collection of my commonly-used C types and functions.

Everything should be compatible with GCC and Clang on Windows and Linux, but I typically only build and test with GCC on Linux. Some features may only be present for specific environments (namely, GCC on Linux).

No attempt is made to ensure safe sharing across threads.

#Table of Contents


All source code is licensed under the terms of the MPL 2.0 license.

#Running Tests

Requires xmake to run tests:

$ xmake -w && xmake run test


#Standalone Source Files

Most source files are independent so you can simply drop the source and header files you want into your current project. The header files document any dependencies that a given module may have.

Most files have an optional dependency on ss_assert.h.

#xmake Package

You can create an xmake package:

$ xmake package ss_utils -o /my/xmake/packages

And then use it in your xmake.lua file:

add_rules("mode.debug", "mode.release")


    if is_mode("debug")
        -- This is needed for backtraces on failed assertions

#Source Overview

The headers contain API documentation and usage notes.


ss_array is a header-only, typesafe, dynamically-sized array type that manages its own memory. There is a partition function but no sort function.

Use the GENERATE_ARRAY macro to create an array for a given type, or the GENERATE_ARRAY2 macro if you need an array named differently than the type:

struct ss_array_int *a1 = ss_array_int_create();

GENERATE_ARRAY2(int*, intptr)
struct ss_array_intptr *a2 = ss_array_intptr_create();

The DECLARE_ARRAY and DECLARE_ARRAY2 macros provide equivalent struct and function declarations so you can create an opaque type in a header and avoid exposing the private swap function.


Required: ss_math.h for next_pow_of_two

Optional: ss_assert.h


ss_assert.h provides an alternative assert function, optionally with a message.

The other source files only use ss_assert if USE_SS_LIB_ASSERT is defined; otherwise they use the assert function from assert.h.

With Glib, ss_assert provides a short backtrace, or a full backtrace if SS_FULL_BACKTRACE is defined.

ss_assert.h also provides an ss_check macro that prints a message but does not abort if a condition is false. This can be helpful during printf-style debugging to avoid outputting noise when the environment state is as expected.


The math module currently only contains a function to calculate the nearest power of two of a number.


ss_string is a true string type that manages its own memory. ss_strings are guaranteed to be NULL-terminated, so you can obtain the pointer to the underlying string via ss_string_as_cstring and pass it to any function expecting a string. Such a function must not modify the length of the string.


Required: ss_math.h for next_pow_of_two

Optional: ss_assert.h


The official repository is at https://git.sr.ht/~rjframe/utility_belt_c; please send any bug reports, patches, or other communications to https://lists.sr.ht/~rjframe/public as I likely will not be checking the Github mirror often.

#Code Styles

  • Postfix the names of private members in public headers with an underscore.
  • Do not typedef the struct keyword away. That's a decision for user code.
  • Use fixed integral types rather than int, long, etc.
  • Use size_t for index or positional values.
  • Use a hard 80-column line width and spaces for indentation.