firstworks Programming with Rudiments using the linkedlist class

Using the linkedlist class

- Introduction
- Manipulating Values
- Manipulating Nodes
- Sorting
- Iterating Manually
- Data Types

### Introduction

The linkedlist class allows you to store an arbitrary number of values in a doubly-linked list. Since the linkedlist class is template-based, you can store arbitrary types of values.

Each linkedlist is composed of a series of linkedlistnodes. Each linkedlistnode contains a value.

### 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);
> // length
> stdoutput.printf("The list contains %lld nodes.\n\n",ll.getLength());
> // print the list
> stdoutput.write("Current contents:\n");
> ll.print();
> stdoutput.write('\n');
> // print the first 3 values in the list
> stdoutput.write("First 3 values:\n");
> ll.print(3);
> stdoutput.write('\n');
> // clear the list
> ll.clear();
> stdoutput.printf("The list contains %lld nodes after clearing it.\n",
> ll.getLength());
> }

### 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));
> // length
> stdoutput.printf("The list contains %lld nodes.\n\n",ll.getLength());
> // print the list
> stdoutput.write("Current contents:\n");
> ll.print();
> stdoutput.write('\n');
> // print the first 3 values in the list
> stdoutput.write("First 3 values:\n");
> ll.print(3);
> 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.generateNumber(&num);
> llis.append(num);
> llhs.append(num);
> }
> // sort one list using insertion sort
> stdoutput.printf("sorting using insertion sort...\n");
> llis.insertionSort();
> // sort one list using heap sort
> stdoutput.printf("sorting using heap sort...\n");
> llhs.heapSort();
> // print the lists
> stdoutput.printf("insertion sorted list\n");
> llis.print(5);
> stdoutput.write("...\n\n");
> // print the list
> stdoutput.printf("heap sorted list\n");
> llhs.print(5);
> 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 (linkedlistnode<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 (linkedlistnode<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;
> linkedlist< myclass * > oll;
> // 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.print();
> stdoutput.write('\n');
> stdoutput.printf("list of 64-bit integers:\n");
> i16ll.print();
> stdoutput.write('\n');
> stdoutput.printf("list of strings:\n");
> i16ll.print();
> stdoutput.write('\n');
> // manually print the list of objects
> stdoutput.printf("list of objects:\n");
> for (linkedlistnode< myclass * > *n=oll.getFirst(); n; n=n->getNext()) {
> n->getValue()->print();
> }
> stdoutput.write('\n');
> // clean up
> for (linkedlistnode< char * > *n=sll.getFirst(); n; n=n->getNext()) {
> delete[] n->getValue();
> }
> for (linkedlistnode< myclass * > *n=oll.getFirst(); n; n=n->getNext()) {
> delete n->getValue();
> }
> }