mirror of
https://github.com/mfocko/blog.git
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264 lines
7.2 KiB
C
264 lines
7.2 KiB
C
#include <assert.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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/* If you want to see arrays before and after sorting, uncomment next line */
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// #define DEBUG_OUTPUT
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/**
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* @brief Swaps two elements at given addresses of given size.
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* @param left Pointer to the first element.
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* @param right Pointer to the second element.
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* @param size Size of the memory one element takes.
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*/
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void swap(void *left, void *right, size_t size)
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{
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/* TODO */
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}
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/**
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* @brief Get index of biggest element in the array.
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* @param ptr Pointer to the first element of the array.
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* @param count Count of the elements in the array.
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* @param size Size of one element in the array.
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* @param comp Comparator that is used to decide ordering of the elements.
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* @returns Index of the biggest element given the ordering.
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*/
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size_t maximum(void *ptr, size_t count, size_t size, int (*comp)(const void *, const void *))
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{
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/* Pseudocode:
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* ===========
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* max_index <- 0
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* FOR i <- 1 TO n - 1 DO
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* IF A[i] > A[max_index] THEN
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* max_index <- i
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* FI
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* OD
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* RETURN max_index
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*/
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/* TODO */
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return 0;
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}
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/**
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* @brief Sort array in-situ using select-sort.
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* @param ptr Pointer to the first element of the array.
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* @param count Count of the elements in the array.
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* @param size Size of one element in the array.
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* @param comp Comparator that is used to decide ordering of the elements.
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*/
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void select_sort(void *ptr, size_t count, size_t size, int (*comp)(const void *, const void *))
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{
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/* Pseudocode:
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* ===========
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* FOR i <- n - 1 DOWNTO 1 DO
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* j <- MAXIMUM(A, i + 1)
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* SWAP(A, i, j)
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* OD
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*/
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/* TODO */
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}
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/**
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* @brief Compares two integers that are given through generic pointers.
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* @param x Pointer to the integer x.
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* @param y Pointer to the integer y.
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* @returns 0 if x == y, <0 if x < y, >0 otherwise.
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*/
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static int int_comparator(const void *x, const void *y)
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{
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/* TODO */
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return 1;
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}
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/**
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* @brief Compares two characters by ASCII value.
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* @param x Pointer to the character x.
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* @param y Pointer to the character y.
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* @returns 0 if x == y, <0 if x < y, >0 otherwise.
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*/
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static int char_comparator(const void *x, const void *y)
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{
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char x_value = *(const char *) x;
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char y_value = *(const char *) y;
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return x_value - y_value;
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}
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/**
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* @brief Compares two characters by ASCII value in a reversed order.
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* @param x Pointer to the character x.
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* @param y Pointer to the character y.
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* @returns 0 if x == y, >0 if x < y, <0 otherwise.
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*/
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static int char_reversed_comparator(const void *x, const void *y)
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{
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char x_value = *(const char *) x;
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char y_value = *(const char *) y;
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return y_value - x_value;
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}
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// #pragma region TESTS
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/**
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* @brief Check if array is sorted.
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* @param ptr Pointer to the first element of the array.
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* @param count Count of the elements in the array.
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* @param size Size of one element in the array.
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* @param comp Comparator that is used to decide ordering of the elements.
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*/
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static void check_if_sorted(void *ptr, size_t count, size_t size, int (*comp)(const void *, const void *))
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{
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char *left = ptr;
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char *right = (char *) ptr + size;
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for (size_t i = 0; i < count - 1; i++) {
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assert(comp(left, right) <= 0);
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left += size;
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right += size;
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}
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}
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#ifdef DEBUG_OUTPUT
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/**
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* @brief Print numbers from an array.
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* @param array Pointer to the first element of the array.
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* @param count Count of the elements in the array.
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*/
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static void print_numbers(int *array, size_t count)
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{
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for (size_t i = 0; i < count; i++) {
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printf(" %d", array[i]);
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}
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}
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#endif
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/**
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* @brief Run some basic tests on integer arrays.
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*/
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static void check_int_arrays()
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{
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/* You are free to add any other examples you like, in case you want to add
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* array with more than 10 elements, please adjust the size.
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*/
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size_t examples_count = 5;
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int examples[][10] = {
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{ -1, 50, -10, 20, 30, 0, -100 },
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{ -100, 0, 30, 20, -10, 50, -1 },
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{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 },
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{ -1, -2, -3, -4, -5, -6, -7, -8, -9, -10 },
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{ 0, 0, 0, 0, 0, 0, 0, 0 }
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};
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printf("[TEST] Integer arrays\n");
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for (size_t i = 0; i < examples_count; i++) {
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size_t count = sizeof(examples[i]) / sizeof(int);
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#ifdef DEBUG_OUTPUT
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printf("Before sorting:");
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print_numbers(examples[i], count);
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putchar('\n');
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#endif
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select_sort(examples[i], count, sizeof(int), int_comparator);
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#ifdef DEBUG_OUTPUT
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printf("After sorting:");
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print_numbers(examples[i], count);
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printf("\n\n");
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#endif
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check_if_sorted(examples[i], count, sizeof(int), int_comparator);
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}
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printf("[PASS] Tests passed.\n\n");
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}
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/**
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* @brief Run some basic tests on strings. Also with reversed ordering.
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*/
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static void check_char_arrays()
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{
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#define MAX_SIZE 20
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/* You are free to add any other examples you like, in case you want to add
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* strings with more than 10 characters, please adjust the size.
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* mind the terminator ;)
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*/
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const size_t examples_count = 5;
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char examples[][MAX_SIZE] = {
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"Hello World!",
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"hi",
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"aloha",
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"LET US SORT",
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"LeT uS sOrT"
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};
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printf("[TEST] Char arrays\n");
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for (size_t i = 0; i < examples_count; i++) {
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size_t count = strlen(examples[i]);
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char temp_array[MAX_SIZE];
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strncpy(temp_array, examples[i], MAX_SIZE);
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select_sort(temp_array, count, 1, char_comparator);
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#ifdef DEBUG_OUTPUT
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printf("Before sorting: \"%s\"\n", examples[i]);
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printf("After sorting: \"%s\"\n\n", temp_array);
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#endif
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check_if_sorted(temp_array, count, 1, char_comparator);
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}
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printf("[PASS] Tests passed.\n\n");
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printf("[TEST] Char arrays reversed\n");
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for (size_t i = 0; i < examples_count; i++) {
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size_t count = strlen(examples[i]);
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char temp_array[MAX_SIZE];
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strncpy(temp_array, examples[i], MAX_SIZE);
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select_sort(temp_array, count, 1, char_reversed_comparator);
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#ifdef DEBUG_OUTPUT
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printf("Before sorting: \"%s\"\n", examples[i]);
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printf("After sorting: \"%s\"\n\n", temp_array);
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#endif
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check_if_sorted(temp_array, count, 1, char_reversed_comparator);
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}
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printf("[PASS] Tests passed.\n\n");
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#undef MAX_SIZE
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}
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static void annotate(const char *description, bool result)
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{
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printf("[TEST] %s\n", description);
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assert(result);
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printf("[PASS] Test passed.\n\n");
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}
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static void check_int_comparator()
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{
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int a = 5, b = -10, c = -10;
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annotate("Test comparator for: a > b", int_comparator(&a, &b) > 0);
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annotate("Test comparator for: b < a", int_comparator(&b, &a) < 0);
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annotate("Test comparator for: b = c", int_comparator(&b, &c) == 0);
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annotate("Test comparator for: a = a", int_comparator(&a, &a) == 0);
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annotate("Test comparator for: b = b", int_comparator(&b, &b) == 0);
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annotate("Test comparator for: c = c", int_comparator(&c, &c) == 0);
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}
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// #pragma endregion TESTS
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int main(void)
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{
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/* Neither of those tests check for bad behaviour, like overwriting array
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* with elements satisfying ordering. **I** check those :scheming:
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*/
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check_int_comparator();
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check_int_arrays();
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check_char_arrays();
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return 0;
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}
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