Initial implementation for binary search - still not done.

misc_algorithms/search/binary_search.c

@@ -0,0 +1,36 @@
+/* This file has the implementation of the function for bubble sort. */
+/* Include guards + include statements. */
+#ifndef BINARY_SEARCH_C
+#define BINARY_SEARCH_C
+#include <stdlib.h>
+#include <string.h>
+#include "binary_search.h"
+#include "../utils/swap_void.h"
+#endif /* BINARY_SEARCH_C */
+
+/* Function implementations. */
+/* Actual function doing the search, does not do any sanity-checking! */
+/* index_start is the search start index (inclusive), index_end is the search end index (exclusive). */
+int binary_search_nocheck(void* array, void *value, int (*comparison_function)(const void*, const void*), const int length, size_t size, int index_start, int index_end) {
+	/* Stopping conditions. */
+	if (index_end <= index_start)
+		return (comparison_function(/* FILL THIS IN! */) == 0) ? /* FILL THIS IN! */ : BINARY_SEARCH_INDEX_NOT_FOUND;
+
+	/* Recurse. */
+	return (comparison_function(/* FILL THIS IN! */) == 0) ? /* FILL THIS IN! */ : (comparison_function(/* FILL THIS IN! */) == 1)
+	/* WRITE THE FUNCTION! */
+}
+
+/* Note that if the comparison function is NULL, the array pointer is NULL or the search value is NULL, then the function will quit. */
+/* Note that the comparison function should return 1 if the second argument is larger than the first, zero if they're both equal and -1 otherwise. */
+/* The array's length should be passed in the length argument. */
+/* Size should match a single object's size, and should be > 0. */
+/* The function returns BINARY_SEARCH_INDEX_NOT_FOUND on error or not found, otherwise will return the index of the value. */
+int binary_search(void* array, void *value, int (*comparison_function)(const void*, const void*), const int length, size_t size) {
+	/* Sanity check. */
+	if (array == NULL || value == NULL || comparison_function == NULL || size <= 0 || length <= 0)
+		return BINARY_SEARCH_INDEX_NOT_FOUND;
+
+	/* The values seem to be OK, delegate the search. */
+	return binary_search_nocheck(array, value, comparison_function, length, size);
+}

misc_algorithms/search/binary_search.h

@@ -0,0 +1,11 @@
+/* This header defines the function for binary search in a sorted array. */
+#ifndef BINARY_SEARCH_H
+#define BINARY_SEARCH_H
+
+/* Constants. */
+#define BINARY_SEARCH_INDEX_NOT_FOUND	-1
+
+/* Function definitions. */
+int binary_search_nocheck(void* array, void* value, int (*comparison_function)(const void*, const void*), const int length, size_t size, int index_start, int index_end);
+int binary_search(void* array, void* value, int (*comparison_function)(const void*, const void*), const int length, size_t size);
+#endif /* BINARY_SEARCH_H */

progress_and_notes

@@ -4,6 +4,8 @@ TESTS:
 1) Fix the bug in the single linked list serialization code.
 2) Write tests for doubly-linked list and queue serialization code.
 
+Implement the binary search function.
+
 Future goals:
 Implement more data structures, such as hash tables, hash maps, more trees.
 Implement algorithms to go with said DSs.