Linked list sorting

listsort.cpp

#include <iostream>

struct Entry {
	char name[20];
	unsigned int price;
	Entry *nextEntry;
};

Entry *readAlphabeticList();
Entry *sortByPrice(Entry *list);
void printList(Entry *list);

void insertIntoList(Entry **list, Entry *newEntry, bool (*comparisonFn)(Entry *, Entry *));
void removeFromList(Entry **list, char *name, unsigned int price);
bool compareAlphabetically(Entry *entry, Entry *otherEntry);
bool compareByPrice(Entry *entry, Entry *otherEntry);

Entry *readEntry();

int main() {
	Entry *list = readAlphabeticList();
	
	std::cout << "Alphabetically ordered list" << std::endl;
	printList(list);

	auto priceSortedList = sortByPrice(list);
	
	std::cout << "Price ordered list:" << std::endl;
	printList(priceSortedList);

	std::cout << "Enter the name of toy which you want to delete and its price or \"end\":" << std::endl;
	
	auto deletedEntry = readEntry();
	if (deletedEntry) {
		removeFromList(&priceSortedList, deletedEntry->name, deletedEntry->price);
	}
	printList(priceSortedList);

	std::cout << "Enter the name of toy which you want to add and its price or \"end\":" << std::endl;
	
	auto addedEntry = readEntry();
	if (addedEntry) {
		insertIntoList(&priceSortedList, addedEntry, compareByPrice);
	}

	printList(priceSortedList);

	return 0;
}

Entry *readEntry() {
	char input[20];
	std::cin >> input;

	if (std::strcmp(input, "end") == 0) return NULL;

	auto entry = new Entry();
	std::strncpy(entry->name, input, sizeof(entry->name));

	std::cin >> entry->price;

	return entry;
}

void printList(Entry *list) {
	auto currEntry = list;
	while (currEntry) {
		std::cout << currEntry->name << ": " << currEntry->price << std::endl;
		currEntry = currEntry->nextEntry;
	}
}

Entry *readAlphabeticList() {
	Entry *list = NULL;

	std::cout << "Enter the name of toy and its price or \"end\"" << std::endl;
	while (true) {
		auto newEntry = readEntry();
		if (!newEntry) break;
		insertIntoList(&list, newEntry, compareAlphabetically);
	}

	return list;
}

void insertIntoList(Entry **list, Entry *newEntry, bool (*comparisonFn)(Entry *, Entry *)) {
	Entry *prevEntry = NULL;
	Entry *currEntry = *list;
	while (currEntry != NULL && comparisonFn(newEntry, currEntry)) {
		prevEntry = currEntry;
		currEntry = currEntry->nextEntry;
	}

	if (prevEntry != NULL) {
		prevEntry->nextEntry = newEntry;
	} else {
		*list = newEntry;
	}

	newEntry->nextEntry = currEntry;
}

bool compareAlphabetically(Entry *entry, Entry *otherEntry) {
	return std::strcmp(entry->name, otherEntry->name) > 0;
}

bool compareByPrice(Entry *entry, Entry *otherEntry) {
	return entry->price > otherEntry->price;
}

Entry *sortByPrice(Entry *list) {
	Entry *newList = NULL;
 
	auto entry = list;
	while (entry) {
		auto newEntry = new Entry;
		*newEntry = *entry;
		insertIntoList(&newList, newEntry, compareByPrice);

		entry = entry->nextEntry;
	}

	return newList;
}

void removeFromList(Entry **list, char *name, unsigned int price) {
	Entry *prevEntry = NULL;
	auto entry = *list;
	while (entry) {
		if (std::strcmp(entry->name, name) == 0 && entry->price == price) {
			if (prevEntry) {
				prevEntry->nextEntry = entry->nextEntry;
			} else {
				*list = entry->nextEntry;
			}
			delete entry;
			break;
		}

		prevEntry = entry;
		entry = entry->nextEntry;
	}
}