Using the linkedlist class

Introduction

Manipulating Values

The linkedlist class provides methods for prepending, appending, inserting and removing values from a linked list, for finding values in the list, for getting the size of the list, clearing the list, and printing the list.

#include <rudiments/linkedlist.h>
#include <rudiments/stdio.h>

int main(int argc, const char **argv) {

	linkedlist<uint32_t>	ll;

	// apppend values to the list
	ll.append(5);
	ll.append(6);
	ll.append(7);

	// prepend values to the list
	ll.prepend(2);
	ll.prepend(1);
	ll.prepend(-1);
	ll.prepend(-2);
	ll.prepend(-2);
	ll.prepend(-2);

	// insert values before and after other values
	ll.insertAfter(ll.find(2),4);
	ll.insertBefore(ll.find(4),3);

	// remove values from the list
	ll.remove(-1);

	// remove all of a particular value from the list
	ll.removeAll(-2);

	// count
	stdoutput.printf("The list contains %lld nodes.\n\n",ll.getCount());

	// print the list
	stdoutput.write("Current contents:\n");
	ll.write();
	stdoutput.write('\n');

	// clear the list
	ll.clear();
	stdoutput.printf("The list contains %lld nodes after clearing it.\n",
								ll.getCount());
}

Manipulating Nodes

The linkedlist class also provides methods for manipulating list nodes directly.

#include <rudiments/linkedlist.h>
#include <rudiments/stdio.h>

int main(int argc, const char **argv) {

	linkedlist<uint32_t>	ll;

	// apppend nodes to the list
	ll.append(new linkedlistnode<uint32_t>(5));
	ll.append(new linkedlistnode<uint32_t>(6));
	ll.append(new linkedlistnode<uint32_t>(7));

	// prepend nodes to the list
	ll.prepend(new linkedlistnode<uint32_t>(2));
	ll.prepend(new linkedlistnode<uint32_t>(1));
	ll.prepend(new linkedlistnode<uint32_t>(0));

	// insert nodes before and after other nodes
	ll.insertAfter(ll.find(2),new linkedlistnode<uint32_t>(4));
	ll.insertBefore(ll.find(4),new linkedlistnode<uint32_t>(3));

	// move nodes around
	ll.append(new linkedlistnode<uint32_t>(-1));
	ll.append(new linkedlistnode<uint32_t>(-2));
	ll.append(new linkedlistnode<uint32_t>(-3));
	ll.moveBefore(ll.find(0),ll.find(-3));
	ll.moveBefore(ll.find(0),ll.find(-2));
	ll.moveAfter(ll.find(-2),ll.find(-1));

	// count
	stdoutput.printf("The list contains %lld nodes.\n\n",ll.getCount());

	// print the list
	stdoutput.write("Current contents:\n");
	ll.write();
	stdoutput.write('\n');
}

Sorting

The linkedlist class also provides methods for sorting the list.

Methods for both insertion and heap sort are provided. Insertion sort is slow, for large lists, but doesn't require any additional memory. Heap sort is fast, even for large lists, but requires additional memory.

#include <rudiments/linkedlist.h>
#include <rudiments/randomnumber.h>
#include <rudiments/stdio.h>

int main(int argc, const char **argv) {

	linkedlist<uint32_t>	llis;
	linkedlist<uint32_t>	llhs;

	// generate random numbers and append them to the lists
	randomnumber	rr;
	rr.setSeed(randomnumber::getSeed());

	stdoutput.printf("generating numbers...\n");
	for (uint16_t i=0; i<20000; i++) {

		uint32_t	num;
		rr.generate(&num);

		llis.append(num);
		llhs.append(num);
	}

	// sort one list inexpensively
	stdoutput.printf("sorting inexpensively...\n");
	llis.sortInexpensively();

	// sort one list quickly
	stdoutput.printf("sorting quickly...\n");
	llhs.sortQuickly();

	// print the lists
	stdoutput.printf("inexpensively sorted list\n");
	llis.write();
	stdoutput.write("...\n\n");
	stdoutput.printf("quickly sorted list\n");
	llhs.write();
	stdoutput.write("...\n\n");
}

Iterating Manually

The linkedlist class also provides methods for manually iterating through the list.

#include <rudiments/linkedlist.h>
#include <rudiments/stdio.h>

int main(int argc, const char **argv) {

	linkedlist<uint32_t>	ll;

	// apppend values to the list
	for (uint32_t i=0; i<20; i++) {
		ll.append(i);
	}

	// print the list forwards, all on one line
	stdoutput.write("forwards:\n");
	for (listnode<uint32_t> *n=ll.getFirst(); n; n=n->getNext()) {
		stdoutput.printf("%d ",n->getValue());
	}
	stdoutput.write("\n\n");

	// print the list backwards, all on one line
	stdoutput.write("backwards:\n");
	for (listnode<uint32_t> *n=ll.getLast(); n; n=n->getPrevious()) {
		stdoutput.printf("%d ",n->getValue());
	}
	stdoutput.write("\n\n");
}

Data Types

Since the linkedlist class is template-based, it can store any type of data.

Note that the print() method works for primitive types and strings, but for more complex types, it only prints the address of the object.

Note also that the linkedlist class does not manage the data stored in it. If you store a list of dynamically allocated strings or objects, they will not be deleted automatically when a node is removed or when the list is cleared. They must be deleted manually.

#include <rudiments/linkedlist.h>
#include <rudiments/stdio.h>


// Define a simple class.  Instances of it will be stored in a list later.
class myclass {
	public:
			myclass(int64_t v) { value=v; }
		void	print() { stdoutput.printf("value: %lld\n",value); }
	private:
		int64_t	value;
};


int main(int argc, const char **argv) {

	// lists of various types
	linkedlist<int16_t>	i16ll;
	linkedlist<int64_t>	i64ll;
	linkedlist< char * >	sll;
	sll.setManageArrayValues(true);
	linkedlist< myclass * >	oll;
	oll.setManageValues(true);

	// populate the lists
	for (int64_t i=0; i<20; i++) {
		i16ll.append(i);
		i64ll.append(i);
		sll.append(charstring::parseNumber(i));
		oll.append(new myclass(i));
	}

	// print the lists of primitive types
	stdoutput.printf("list of 16-bit integers:\n");
	i16ll.write();
	stdoutput.write('\n');

	stdoutput.printf("list of 64-bit integers:\n");
	i16ll.write();
	stdoutput.write('\n');

	stdoutput.printf("list of strings:\n");
	i16ll.write();
	stdoutput.write('\n');

	// manually print the list of objects
	stdoutput.printf("list of objects:\n");
	for (listnode< myclass * > *n=oll.getFirst(); n; n=n->getNext()) {
		n->getValue()->print();
	}
	stdoutput.write('\n');

	// clean up
	sll.clear();
	oll.clear();
}