👀 Views: 3 💬 Answers: 1 📅 Created: 2025-06-06

c sorting qsort gcc C

I'm upgrading from an older version and After trying multiple solutions online, I still can't figure this out. I'm using the `qsort` function from the standard library to sort an array of structures in C, but I'm getting unexpected results where the array remains unsorted... I'm compiling my code on Ubuntu 22.04 with GCC version 11.2.0. I've defined a structure for student records and implemented a comparison function to sort by GPA. Here’s the relevant part of my code: ```c #include <stdio.h> #include <stdlib.h> typedef struct { char name[50]; float gpa; } Student; int compare(const void *a, const void *b) { Student *studentA = (Student *)a; Student *studentB = (Student *)b; return (studentA->gpa > studentB->gpa) - (studentA->gpa < studentB->gpa); } int main() { Student students[] = { {"Alice", 3.5}, {"Bob", 3.9}, {"Charlie", 3.2} }; size_t n = sizeof(students) / sizeof(students[0]); qsort(students, n, sizeof(Student), compare); for (size_t i = 0; i < n; i++) { printf("%s: %.2f\n", students[i].name, students[i].gpa); } return 0; } ``` I expect to see the students sorted by GPA in ascending order, but the output is still the same as the original array. I've double-checked the comparison logic and the types being cast. I even tried changing the comparison function to return the difference between the GPAs directly, but it didn't fix the scenario. Running the program yields the following output: ``` Alice: 3.50 Bob: 3.90 Charlie: 3.20 ``` What could be wrong with my implementation, or have I missed something crucial about how `qsort` works? My development environment is Linux. Thanks in advance! Any ideas what could be causing this? For context: I'm using C on Windows 11. Cheers for any assistance!