C //练习 6-3 编写一个交叉引用程序，打印文档中所有单词的列表，并且每个单词还有一个列表，记录出现过该单词的行号。对the、and等非实义单词不予考虑。

C程序设计语言 （第二版） 练习 6-3

练习 6-3 编写一个交叉引用程序，打印文档中所有单词的列表，并且每个单词还有一个列表，记录出现过该单词的行号。对the、and等非实义单词不予考虑。

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

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代码块：

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAXWORD 100
#define BUFSIZE 100

char buf[BUFSIZE];
int bufp = 0;
long lineNumber = 1;

struct tnode{
    char *word;
    struct tnode *left;
    struct tnode *right;
    int count;
    long lineNumbers[];
};

int judge(char *s){
    int found = 0;
    int giveup = 0;

    char *list[] = {"a", "an", "and", "be", "but", "by", "he", "I", "is", "it", "of", "off", "on", "she", "so", "the", "they", "to", "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 = 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;
}

struct tnode *talloc(void) {
    return (struct tnode *) malloc(sizeof(struct tnode));
}

char *_strdup(char *s) {
    char *p;

    p = (char *) malloc(strlen(s) + 1);
    if (p != NULL)
        strcpy(p, s);
    return p;
}

struct tnode *addtree(struct tnode *p, char *w, long lineNumber) {
    int i, cond;

    if(p == NULL){
        p = talloc(); 
        p->word = _strdup(w);
        p->count = 1;
        p->lineNumbers[p->count - 1] = lineNumber;
        p-> left = p->right = NULL;
    }
	else{
        cond = strcmp(w, p->word);
        if(cond == 0){
            for(i = 0; i < p->count; i++){
                if(lineNumber == p->lineNumbers[i]){
                    return p;
				}
			}
            p->lineNumbers[p->count] = lineNumber;
            p->count += 1;
        }
		else if(cond < 0){
            p->left = addtree(p->left, w, lineNumber);
		}
        else{
            p->right = addtree(p->right, w, lineNumber);
		}
    }
    return p;
}

void treeprint(struct tnode *p) {
    int i;
    if(p != NULL){
        treeprint(p->left);

        if(p->count > 1 && strlen(p->word) > 1){
            printf("%12s:\t", p->word);
            for(i = 0; i < p->count; i++){
                printf("%lu%s", p->lineNumbers[i], (i == p->count - 1) ? "\n" : ", ");
			}
        }

        treeprint(p->right);
    }
}

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;

    while(isspace(c = getch())){
        if (c == '\n'){
            lineNumber++;
		}
	}

    if(c != EOF){
        *w++ = c;
	}

    if(!isalpha(c)){
        *w = '\0';
        return c;
    }

    for(;--lim > 0; w++){
        if(!isalpha(*w = getch())){
            ungetch(*w);
            break;
		}
	}
    *w = '\0';
    return word[0];
}

int main(){
    struct tnode *root;
    char word[MAXWORD];

    root = NULL;
    while (getword(word, MAXWORD) != EOF){
        if (isalpha(word[0]) && !judge(word)){
            root = addtree(root, word, lineNumber);
		}
	}
    treeprint(root);

	system("pause");
    return 0;
}