The following code shows a data type agnostic bubble sort implementation. The purpose of the example is to bring out similarities with the qsort() function call and show why we need to create a comparison function.
C
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/** * File: agnostic_bubble.c * Author: Risto Heinsar * Created: 02.03.2025 * Modified 06.03.2025 * * Description: Example shows data type agnostic bubble sort. Used too show * similarities with qsort() function parameters. */ #include <stdio.h> #include <stdbool.h> #include <string.h> #define STR_LEN 64 typedef unsigned char byte; struct Student { char name[STR_LEN]; int score; }; int ComparInt(const void *pA, const void *pB); int ComparStudentScore(const void *pA, const void *pB); void BubbleSort(void *data, size_t n, size_t size, int(*Compar)(const void *a, const void *b)); void PrintIntArr(int *data, int n); void PrintStudents(struct Student *data, int n); int main(void) { int vals[] = {1, 9, 2, 8, -5, 14}; int nVals = sizeof(vals) / sizeof(int); struct Student students[] = {{"Mari", 75}, {"Kati", 50}, {"Mihkel", 85}, {"Priit", 45}, {"Tiina", 68}}; int nStudents = sizeof(students) / sizeof(struct Student); BubbleSort(vals, (size_t)nVals, sizeof(int), ComparInt); BubbleSort(students, (size_t)nStudents, sizeof(struct Student), ComparStudentScore); PrintIntArr(vals, nVals); PrintStudents(students, nStudents); return 0; } /** * Description: Data type agnostic bubble sort * * Parameters: data - array with items to sort * n - number of items * size - size in bytes for each item * Compar - comparison function to identify order of items * * Return: none */ void BubbleSort(void *data, size_t n, size_t size, int(*Compar)(const void *a, const void *b)) { /* End correction to avoid overflow in comparison */ n = n - 1; while (1) { bool sorted = true; for (size_t i = 0; i < n; i++) { /* Calculate pointers for current and next member */ void *pA = data + i * size; void *pB = data + (i + 1) * size; /* Check if items are in the wrong order */ if (Compar(pA, pB) > 0) { /* Swap the two items */ byte temp[size]; memcpy(temp, pA, size); memcpy(pA, pB, size); memcpy(pB, temp, size); sorted = false; } } /* No swaps, array sorted */ if (sorted) return; n--; } } /** * Description: Compares integers based on value * * Parameters: pA - pointer to first integer * pB - pointer to second integer * * Return: < 0 pA has higher value, comes first * = 0 if order doesn't matter * > 0 pB has higher value, comes first */ int ComparInt(const void *pA, const void *pB) { return *(int *)pA - *(int *)pB; } /** * Description: Compares students based on score, descending order * * Parameters: pA - first student struct pointer * pB - pointer to the second student struct * * Return: < 0 pA has higher score, comes first * = 0 if order doesn't matter * > 0 pB has higher score, comes first */ int ComparStudentScore(const void *pA, const void *pB) { return ((struct Student *)pB)->score - ((struct Student *)pA)->score; } /** * Description: Prints the integer array on screen * * Parameters: data - integer array * n - number of integers * * Return: none */ void PrintIntArr(int *data, int n) { printf("Sorted array (asc):\n"); for (int i = 0; i < n; i++) { printf("%d ", data[i]); } printf("\n\n"); } /** * Description: Prints the student struct array on screen * * Parameters: data - student struct array * n - number of students * * Return: none */ void PrintStudents(struct Student *data, int n) { printf("Top students:\n"); for (int i = 0; i < n; i++) { printf("%15s %3d\n", data[i].name, data[i].score); } printf("\n"); } |