List Implementation and Manipulation in C, Slides of Computer Engineering and Programming

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Computer Programming Techniques

1. List Data Structures and Operations

2. List Implementations

3. Dynamically Created Lists

4. Converting a String to a List

5. List Functions

Overview

Version 1:

#define N 1000 /* the size of the list */

typedef char LIST[N];

LIST lt; /* same as char lt[N] */

2. List implementations

struct listnode {

char data;

struct listnode *nextptr;

typedef struct listnode

LISTNODE;

LISTNODE elem;

Version 2 (Sec. 12.2)

elem

data nextptr

a.nextptr = &b;

b.nextptr = &c;

printf("%c", a.nextptr->data);

/* 'c' printed */

printf("%c", a.nextptr->nextptr->data);

/* 'e' printed */

a b c

‘a’ ‘c’ ‘e’ NULL

/* list implementation as before */

typedef LISTNODE *LNP;

LNP head = NULL;

head = malloc(sizeof(LISTNODE));

head->data = 'n';

head->nextptr = NULL;

3. Dynamically Created

Lists

Function prototype in stdlib.h:

void *malloc(size_t size);

head

‘n’ NULL

head->nextptr->nextptr =

malloc(sizeof(LISTNODE));

head->nextptr->nextptr->data = 'w';

head->nextptr->nextptr->nextptr = NULL;

Add a third element

head

‘n’ ‘e’ ‘w’ NULL

#include <stdio.h>

#include <stdlib.h>

/* list type implementation */

LNP string_to_list(char []);

int main()

LNP h = NULL;

h = string_to_list("AB");

return 0;

/* implementation of string_to_list() */

4. Converting a String to a

List

head =

malloc(sizeof(LISTNODE));

head->data = s[0];

tail = head;

string_to_list("AB")

head

‘A’

tail

tail->nextptr = malloc(sizeof(LISTNODE));

head

‘A’

tail

s[2] = '\0'

/* so end of list is assigned NULL */

head

‘A’

tail

‘B’ NULL

5 .1. Empty Lists

5 .2. Return the First Element of a List

5 .3. Produce the Tail of a List

5 .4. Put an Element on the Front of a List

5 .5. Insertion

5. List Functions

continued

 Make an empty list:

LNP h1;

h1 = NULL;

 Test for emptiness:

int isempty(LNP sptr)

return (sptr == NULL);

5 .1. Empty Lists

char first(LNP cptr)

if (isempty(cptr))

return '\0'

else

return cptr->data;

5 .2. Return the First Element

of a List