linked-list.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>

struct course {
    char code[10];
    int credit;
    char name[50];
    struct course *next;
};
typedef struct course course;

course* MakeNode(void) {
    struct course* a;
    a = (struct course *)malloc(sizeof(struct course));
    if(a == NULL) {
         puts("Some kind of malloc() error");
         exit(1);
    }
     return a;
}

void AddCourse(course** head_ref, char code[10], int credit, char name[50]) {
    course* c = MakeNode();
    strncpy(c->code, code, 10);
    strncpy(c->name, name, 50);
    c->credit = credit;
    c->next = *head_ref;
    *head_ref = c;
}

void PrintAll(course* head) {
    course* c;
    for (c = head; c != NULL; c = c->next)
        printf("%s \t %d \t %s\n", c->code, c->credit, c->name);
}

bool DeleteCourse(course** head_ref, char code[10]) {
    course *iter = *head_ref;
    course *prev = NULL;
    while (iter->code != code) {
        prev = iter;
        iter = iter->next;
        if (iter == NULL) return false; //out of list but not found
    }
    if (iter == *head_ref) {
        *head_ref = iter->next;
        free(iter);
    } else {
        prev->next = iter->next;
        free(iter); // NUCLEAR BOMB!!!
    }
    return true;
}

void SortByCredit(course* head) {
    // ASCENDING
    for (course *i = head; i != NULL; i = i->next) { 
        // i = 1 to n
        for (course *c = head; c->next != NULL; c = c->next) {
            // c = 1 to n-1
            if (c->credit > c->next->credit) {
                course temp = *c;
                *c = *c->next;
                *c->next = temp;
            }
        }
    }
}