K and R C, Solution to Exercise 6-3:K and R C Programs Exercises provides the solution to all the exercises in the
C Programming Language (2nd Edition). You can learn and solve K&R C Programs Exercise.
C Program to Write a cross-referencer program that prints a list of all words in a document, and, for each word, a list of the line numbers on which it occurs. Remove noise words like “the”, “and,” and so on. Read more about
C Programming Language .
/***********************************************************
* You can use all the programs on www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
* Original URL: http://www.c-program-example.com/2012/02/k-r-c-programs-exercise-6-3.html
* GitHub URL: https://github.com/snadahalli/cprograms/blob/master/knrc/knrc6_3.c
***********************************************************/
/** Write a cross-referencer program that prints a list of all words in a
* document, and, for each word, a list of the line numbers on which it
* occurs. Remove noise words like "the", "and," and so on.
**/
#include
#include
#include
#include
char *dupstr(char *s) {
char *p = NULL;
if(s != NULL){
p = malloc(strlen(s) + 1);
if(p) {
strcpy(p, s);
}
}
return p;
}
int i_strcmp(const char *s, const char *t) {
int diff = 0;
char cs = 0;
char ct = 0;
while(diff == 0 && *s != ' ' && *t != ' ') {
cs = tolower((unsigned char)*s);
ct = tolower((unsigned char)*t);
if(cs < ct) {
diff = -1;
}
else if(cs > ct) {
diff = 1;
}
++s;
++t;
}
if(diff == 0 && *s != *t) {
if(*s == ' ') {
diff = -1;
}
else {
diff = 1;
}
}
return diff;
}
struct linelist {
struct linelist *next;
int line;
};
struct wordtree {
char *word;
struct linelist *firstline;
struct wordtree *left;
struct wordtree *right;
};
void printlist(struct linelist *list) {
if(list != NULL) {
printlist(list->next);
printf("%6d ", list->line);
}
}
void printtree(struct wordtree *node) {
if(node != NULL) {
printtree(node->left);
printf("%18s ", node->word);
printlist(node->firstline);
printf("n");
printtree(node->right);
}
}
struct linelist *addlink(int line) {
struct linelist *new = malloc(sizeof *new);
if(new != NULL) {
new->line = line;
new->next = NULL;
}
return new;
}
void deletelist(struct linelist *listnode) {
if(listnode != NULL) {
deletelist(listnode->next);
free(listnode);
}
}
void deleteword(struct wordtree **node) {
struct wordtree *temp = NULL;
if(node != NULL) {
if(*node != ' ') {
if((*node)->right != NULL) {
temp = *node;
deleteword(&temp->right);
}
if((*node)->left != NULL) {
temp = *node;
deleteword(&temp->left);
}
if((*node)->word != NULL) {
free((*node)->word);
}
if((*node)->firstline != NULL) {
deletelist((*node)->firstline);
}
free(*node);
*node = NULL;
}
}
}
struct wordtree *addword(struct wordtree **node, char *word, int line) {
struct wordtree *wordloc = NULL;
struct linelist *newline = NULL;
struct wordtree *temp = NULL;
int diff = 0;
if(node != NULL && word != NULL) {
if(NULL == *node) {
node = malloc(sizeof **node);
if(NULL != *node) {
(*node)->left = NULL;
(*node)->right = NULL;
(*node)->word = dupstr(word);
if((*node)->word != NULL) {
(*node)->firstline = addlink(line);
if((*node)->firstline != NULL) {
wordloc = *node;
}
}
}
}
else {
diff = i_strcmp((*node)->word, word);
if(0 == diff) {
newline = addlink(line);
if(newline != NULL) {
wordloc = *node;
newline->next = (*node)->firstline;
(*node)->firstline = newline;
}
}
else if(0 < diff) {
temp = *node;
wordloc = addword(&temp->left, word, line);
}
else {
temp = *node;
wordloc = addword(&temp->right, word, line);
}
}
}
if(wordloc == NULL) {
deleteword(node);
}
return wordloc;
}
char *char_in_string(char *s, int c) {
char *p = NULL;
/* if there's no data, we'll stop */
if(s != NULL) {
if(c != ' ') {
while(*s != ' ' && *s != c) {
++s;
}
if(*s == c) {
p = s;
}
}
}
return p;
}
char *tokenise(char **s, char *delims) {
char *p = NULL;
char *q = NULL;
if(s != NULL && *s != ' ' && delims != NULL) {
/* pass over leading delimiters */
while(NULL != char_in_string(delims, **s)) {
++*s;
}
if(**s != ' ') {
q = *s + 1;
p = *s;
while(*q != ' ' && NULL == char_in_string(delims, *q)) {
++q;
}
*s = q + (*q != ' ');
*q = ' ';
}
}
return p;
}
int NoiseWord(char *s)
{
int found = 0;
int giveup = 0;
char *list[] = {
"a",
"an",
"and",
"be",
"but",
"by",
"he",
"I",
"is",
"it",
"off",
"on",
"she",
"so",
"the",
"they",
"you"
};
int top = sizeof list / sizeof list[0] - 1;
int bottom = 0;
int guess = top / 2;
int diff = 0;
if(s != NULL) {
while(!found && !giveup) {
diff = i_strcmp(list[guess], s);
if(0 == diff) {
found = 1;
}
else if(0 < diff) {
top = guess - 1;
}
else {
bottom = guess + 1;
}
if(top < bottom) {
giveup = 1;
}
else {
guess = (top + bottom) / 2;
}
}
}
return found;
}
char *GetLine(char *s, int n, FILE *fp) {
int c = 0;
int done = 0;
char *p = s;
while(!done && --n > 0 && (c = getc(fp)) != EOF) {
if((*p++ = c) == 'n') {
done = 1;
}
}
*p = ' ';
if(EOF == c && p == s) {
p = NULL;
}
else {
p = s;
}
return p;
}
#define MAXLINE 8192
int main(void) {
static char buffer[MAXLINE] = {0};
char *s = NULL;
char *word = NULL;
int line = 0;
int giveup = 0;
struct wordtree *tree = NULL;
char *delims = " tnrafv!"%^&*()_=+{}[]\|/,.<>:;#~?";
while(!giveup && GetLine(buffer, sizeof buffer, stdin) != NULL) {
++line;
s = buffer;
while(!giveup && (word = tokenise(&s, delims)) != NULL) {
if(!NoiseWord(word)) {
if(NULL == addword(&tree, word, line)) {
printf("Error adding data into memory. Giving up.n");
giveup = 1;
}
}
}
}
if(!giveup) {
printf("%18s Line Numbersn", "Word");
printtree(tree);
}
deleteword(&tree);
return 0;
}
Read more c programs
C Basic
C Strings
K and R C Programs Exercise
You can easily select the code by double clicking on the code area above.
To get regular updates on new C programs, you can Follow @c_program
You can discuss these programs on our Facebook Page. Start a discussion right now,
our page!
Share this program with your Facebook friends now! by liking it
(you can send this program to your friend using this button)
Like to get updates right inside your feed reader? Grab our feed!
To browse more C Programs visit this
link
(c) www.c-program-example.com