CS 1723, Word Frequency Program (White Book, Pages 139-143), Wed Oct 28 1998, Page 1 of 2vip% cat tree.c#include <stdio.h>#include <ctype.h>#include <string.h>#include <stdlib.h>#define MAXWORD 100struct tnode { char *word; int count; struct tnode *left; struct tnode *right;};struct tnode *addtree(struct tnode *, char *);void treeprint(struct tnode *);struct tnode *talloc(void);int getword(char *, int);char *strdupl(char *);/* word frequency count */void main(void){ struct tnode *root; char word[MAXWORD]; root = NULL; while (getword(word, MAXWORD) != EOF) if (isalpha(word[0])) root = addtree(root, word); treeprint(root); exit(0);}/* addtree: add a node with w, at or below p */struct tnode *addtree(struct tnode *p, char *w){ int cond; if (p == NULL) { p = talloc(); p -> word = strdupl(w); p -> count = 1; p -> left = p -> right = NULL; } else if ((cond = strcmp(w, p -> word)) == 0) (p -> count)++; else if (cond < 0) p -> left = addtree(p -> left, w); else p -> right = addtree(p -> right, w); return p;}/* treeprint: in-order print of tree p */void treeprint(struct tnode *p){ if (p != NULL) { treeprint(p -> left); printf("%4d %s\n", p -> count, p -> word); treeprint(p -> right); }}/* talloc: make a tnode */struct tnode *talloc(void){ return (struct tnode *) malloc(sizeof(struct tnode));}/* getword: get next word or charcter from input */int getword(char *word, int lim){ int c; char *w = word; while (isspace(c = getchar())) ; if (c != EOF) *w++ = c; if (!isalpha(c)) { *w = ’\0’; return c; } for ( ; --lim > 0; w++) if (!isalpha(*w = getchar())) { ungetc(*w, stdin); break; } *w = ’\0’; return word[0];}/* strdupl: make duplicate of s.(strdup builtin) */char *strdupl(char *s){ char *p; p = (char *) malloc(strlen(s)+1); if (p != NULL) strcpy(p, s); return p;}CS 1723, Word Frequency Program (White Book, Pages 139-143), Wed Oct 28 1998, Page 2 of 2vip% lint -m -u tree.cfunction returns value which is always ignored strcpy printf ungetc vip% cc -o tree tree.cvip% tree <tree.c 2 EOF 3 MAXWORD 5 NULL 3 a 1 add 6 addtree 1 at 1 below 1 break 1 builtin 6 c 13 char 1 charcter 3 cond 5 count 1 ctype 1 d 1 define 1 duplicate 3 else 1 exit 1 for 1 frequency 1 from 1 get 2 getchar 4 getword 4 h 9 if 1 in 4 include 1 input 7 int 1 is 3 isalpha 1 isspace 5 left 2 lim 1 main 2 make 2 malloc 1 n 1 next 1 node 2 of 2 or 1 order 27 p 1 print 1 printf 5 return 5 right 5 root 5 s 1 sizeof 1 stdin 1 stdio 1 stdlib 1 strcmp 1 strcpy 1 strdup 4 strdupl 1 string 1 strlen 14 struct 4 talloc 15 tnode 1 tree 6 treeprint 1 ungetc 6 void 13 w 2 while 1 with 13