Dynamic Array Library

A small, minimal-overhead dynamic array implementation for C, inspired by Per Vognsen's Bitwise series and Sean Barrett's stb_ds.

Features

• Simple API with macros for dynamic array operations
• Custom allocator support
• Minimal boilerplate—just declare a pointer and use it
• Fast push, pop, and access operations
• Optional error handling

API Overview

// Declare an array of any type
int *arr = NULL;

darr_push(arr, 42);
darr_push(arr, 84);

for (int i = 0; i < darr_len(arr); i++) {
    printf("%d: %d\n", i, arr[i]);
}

darr_free(arr); // Free memory when done

Macros & Functions

• darr_push(arr, value) – Append an element, resizing as needed.
• darr_pop(arr) – Remove and return the last element. User should check for NULL and empty array.
• darr_peek(arr) – Return the last element without removing it. User should check for NULL and empty array.
• darr_pop_safe(arr, default) – Safe pop with a default return value if empty.
• darr_peek_safe(arr, default) – Safe peek with a default return value if empty.
• darr_len(arr) – Get the number of elements.
• darr_cap(arr) – Get the capacity.
• darr_clear(arr) – Set length to zero without freeing.
• darr_free(arr) – Free the array.
• darr_init(arr, initial_capacity, allocator) – Initialize with custom capacity and allocator.
• darr_set_error_handler(handler) – Set a custom error handler.

Implementation Details

Dynamic arrays use a small header (DarrHdr) stored before the array data. The user may provides an allocator function.

typedef struct DarrHdr { 
    AllocatorFn alloc; // allocator must provide a single contiguous block of memory
    unsigned int len;
    unsigned int cap;
    _Alignas(DARR_ALIGNMENT) char data[]; 
} DarrHdr;

static inline DarrHdr *darr__hdr(void *arr) { 
    return (DarrHdr*)( (char*)(arr) - offsetof(DarrHdr, data)); 
}

Credits

• Adapted from Per Vognsen's Bitwise series.
• Based on techniques from Sean Barrett's stb_ds.

Per Vognsen's Bitwise Series on YouTube

License

MIT License