#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdlib.h>
#define MAXWORD 100

struct tnode { /* the tree node: */
    char *word; /* points to the text */
    int count; /* number of occurrences */
    struct tnode *left; /* left child */
    struct tnode *right; /* right child */
};


struct tnode *addtree(struct tnode *, char *);
void treeprint(struct tnode *);
int getword(char *, int);
/* word frequency count */

main()
{
    char c;
    struct tnode *root;
    char word[MAXWORD];
    root = NULL;
    while (scanf("%s",word)!=EOF)
        root = addtree(root, word);//这里不太理解，root作为根节点要是被更改了，下次操作时又怎么找到根节点呢？
    treeprint(root);
    return 0;
}


struct tnode *talloc(void);
char *strdup(char *);
/* addtree: add a node with w, at or below p */
struct tnode *addtree(struct tnode *p, char *w)
{
    int cond;
    if (p == NULL) { /* a new word has arrived */
        p = talloc(); /* make a new node */
        p->word = strdup(w);
        p->count = 1;
        p->left = p->right = NULL;
    } else if ((cond = strcmp(w, p->word)) == 0)
        p->count++; /* repeated word */
    else if (cond < 0) /* less than into left subtree */
        p->left = addtree(p->left, w);
    else /* greater than into right subtree */
        p->right = addtree(p->right, w);
    return p;
}


/* treeprint: inorder
print of tree p */
void treeprint(struct tnode *p)
{
    if (p != NULL) {
        treeprint(p->left);
        printf("%d %s\n", p->count, p->word);
        treeprint(p->right);
    }
}


/* talloc: make a tnode */
struct tnode *talloc(void)
{
    return (struct tnode *) malloc(sizeof(struct tnode));
}


char *strdup(char *s) /* make a duplicate of s */
{
    char *p;
    p = (char *) malloc(strlen(s)+1); /* +1 for '\0' */
    if (p != NULL)
        strcpy(p, s);
    return p;
}

 
问题：
main函数里面
root = addtree(root, word)
roo作为根节点每次都被赋了新值，下次又是如何找到根节点的呢
实际运行没有错误
请各位高手指点一下

[ 本帖最后由 阿的个发 于 2012-5-12 20:43 编辑 ]

贴上完整代码，运行没问题，请高手解惑

求人不如靠己啊 连个回帖的都没有 自己搞明白了