This is a very simple library for implementing a Min-Heap or Priority Queue in plain C. It should be very understandable, and is a useful reference for people who are learning C or want to understand the binary heap data structure.

This implementation makes use of a plain array to store the table. It supports resizing (growing and shrinking) and does this by simply doubling or halving the array size when appropriate. This was make as a counter part to a different project, c-minheap-indirect which utilizes an indirection table to increase memory efficiency. This is an important distinction when the number of elements is very large, as this implementation will have large amounts of wasted space, and relies on expensive doubling operations, while the indirect implementation has very cheap resizing operations and wastes less than a single page worth of memory.

To use the library you only need to include the heap.h header, and link against the heap.c file. There is nothing fancy required.

Included in the project is a file main.c which serves as a simple test file. We randomly generate a large number of keys (variable, default to 10M), and insert them into our heap. We then extract the keys and verify they are ordered. To test this, just run make and then run the test program.