C程序设计语言 （第二版） 练习 6-4

练习 6-4 编写一个程序，根据单词的出现频率按降序打印输入的各个不同单词，并在每个单词的前面标上它的出现次数。

注意：代码在win32控制台运行，在不同的IDE环境下，有部分可能需要变更。

IDE工具：Visual Studio 2010

 

代码块：

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include <limits.h>#define MAXWORD 1000
#define BUFSIZE 100
#define IN 1
#define OUT 0char buf[BUFSIZE];
int bufp = 0;struct tnode {char *word;int count;struct tnode *left;struct tnode *right;
};struct wnode {int number;struct words *words;struct wnode *left;struct wnode *right;
};struct words {char *word;struct words *next;
};int getch(void){return (bufp > 0) ? buf[--bufp] : getchar();
}void ungetch(int c){if(bufp >= BUFSIZE){printf("ungetch: too many characters\n");}else{buf[bufp++] = c;}
}int getword(char *word, int lim){int c;char *w = word;static int lineBeginning = 1; static int afterSlash = 0;int afterStar = 0;if(isspace(c = getch())){afterSlash = 0;}while(isspace(c)){if(c == '\n'){lineBeginning = 1;}c = getch();}if(c != EOF){*w++ = c;}if(c == '#' && lineBeginning == 1){while((c = getch()) != '\n' && c != EOF);return getword(word, lim);}lineBeginning = 0;if(c == '\\'){afterSlash = afterSlash ? 0 : 1;}else if(c == '/' ){if((c = getch()) == '*' && !afterSlash){while((c = getch()) != EOF){if(c == '/'){if(afterStar){return getword(word, lim);}}else if(c == '*' && !afterSlash){afterStar = 1;}else if(c == '\\'){afterSlash = afterSlash ? 0 : 1;}else{afterStar = 0;afterSlash = 0;}}}afterSlash = 0;if(c != EOF){ungetch(c);}}else if(c == '\"'){if(!afterSlash){--w;while((c = getch()) != EOF){if(c == '\"' && !afterSlash){break;}else if(c == '\\'){afterSlash = afterSlash ? 0 : 1;}else{afterSlash = 0;}*w++ = c;}*w = '\0';if(c == EOF){return EOF;}else{return getword(word, lim);}}afterSlash = 0;}if(!isalpha(c) && c != '_'){*w = '\0';if(c != '\\'){afterSlash = 0;}return c;}afterSlash = 0;for( ; --lim > 0; ++w){if(!isalnum(*w = getch()) && *w != '_'){ungetch(*w);break;}}*w = '\0';return word[0];
}struct tnode *talloc(void) {return (struct tnode *)malloc(sizeof(struct tnode));
}struct wnode *numwordalloc(void) {return (struct wnode *)malloc(sizeof(struct wnode));
}struct words *wordsalloc(void) {return (struct words *)malloc(sizeof(struct words));
}char *_strdup(char *s) {char *p;p = (char *)malloc(strlen(s) + 1);if(p != NULL){strcpy(p, s);}return p;
}void printwords(const struct words* w, const int count) {if (w != NULL) {printf("%4d\t%s\n", count, w->word);w = w->next;}
}void treeprint(const struct wnode *p) {if(p != NULL){treeprint(p->left);printwords(p->words, p->number);treeprint(p->right);}
}struct tnode *addtree(struct tnode *p, char *w) {int cond;if(p == NULL){p = talloc();p->word = _strdup(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;
}struct words *addword(struct words* list, char *w) {if(list == NULL){list = wordsalloc();list->word = _strdup(w);list->next = NULL;} else{list->next = addword(list->next, w);}return list;
}struct wnode *addwtree(struct wnode *p, int count, char* w) {if(p == NULL){p = numwordalloc();p->number = count;p->words = NULL;p->words = addword(p->words, w);}else if(count > p->number){p->left = addwtree(p->left, count, w);}else{p->right = addwtree(p->right, count, w);}return p;
}struct wnode *traverse(const struct tnode *p, struct wnode *q) {if(p != NULL){q = traverse(p->left, q);q = addwtree(q, p->count, p->word);q = traverse(p->right, q);}return q;
}int main() {struct tnode *root;struct wnode *wroot;char word[MAXWORD];root = NULL;wroot = NULL;while(getword(word, MAXWORD) != 'x')if(isalpha(word[0]))root = addtree(root, word);wroot = traverse(root, wroot);treeprint(wroot);return 0;
}