我正在尝试完成一项作业,但遇到了一些问题。我必须编写一个程序,使用 struct 创建一个链接列表,我必须在其中添加单词。如果该单词已经在链接列表中,那么我只需更新频率即可。
我已经有了这个:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct words Words;
struct words{
char *word;
int freq;
Words *next;
};
/*
Inserts a copy of newWord into the list, in lexicographical order. If newWord is already
in the list, increment the freq member of the node. The function returns a pointer to
the list.
*/
Words *addWord(Words *headPtr, char* newWord){
Words *current = headPtr;
if(headPtr == NULL)
{
current->word = newWord;
current->freq = 1;
}
else
{
while(current != NULL)
if(strcmp(headPtr->word, newWord))
{
current->freq++;
return headPtr;
}
else
{
current->word = newWord;
current->freq = 1;
}
}
return headPtr;
}
//prints the words in the list, along with the frequency of each word
void printWords(Words *headPtr){
while(headPtr != NULL)
{
printf("%s: %d", headPtr->word, headPtr->freq);
headPtr = headPtr->next;
}
}
//frees the entire list. Note: Words **headPtr since the headPtr NULL upon return
void deleteList(Words **headPtr){
Words *current = *headPtr;
Words *next;
while(current != NULL)
{
next = current->next;
free(current);
current = next;
}
*headPtr = NULL;
}
int main(){
char word[20];
Words *list = NULL;
scanf("%s", word);
while(!feof(stdin)){
list = addWord(list, word);
scanf("%s", word);
}
printWords(list);
deleteList(&list);
}
最佳答案
您的代码存在一些问题。查看嵌入到代码中的注释:
Words *addWord(Words *headPtr, char* newWord){
Words *current = (Words*) malloc(sizeof(Words)); // Don't malloc here.
// You don't know yet
// whether you need
// a new node or you
// you just need to
// update freq
if(current == NULL) // If current is NULL you have
// serious problems, i.e. you
// are out of memory.
// Did you really intended to do:
// if (headPtr == NULL)
{
current->word = newWord;
*current->next = (*headPtr);
(*headPtr) = *current; // I'm not sure what you try here
// but it seems strange
}
else
{
while(current != NULL)
if(strcmp(headPtr->word, newWord)) // This is not the way to compare
// strings. Two strings compare
// when "strcmp" returns 0.
//
// Further you don't want to
// use headPtr here.
{
current->freq++; // Use of uninitialized value
return; // Missing argument to return
}
else
{
current->word = newWord; // Use of uninitialized value
*current->next = (*headPtr); // Use of uninitialized value
(*headPtr) = *current;
}
}
// Missing return
}
这里是一些开始的代码:
#define WORD_SIZE 20
struct words{
char word[WORD_SIZE]; // Use a char array
int freq;
Words *next;
};
Words *addWord(Words *headPtr, char* newWord)
{
Words *current = headPtr; // Make a copy of headPtr
Words* new;
if ((current == NULL) || (strcmp(current->word, newWord) > 0))
{
// Insert in front of list
new = malloc(sizeof(Words)); // Allocate memory
if (new == NULL)
{
// oh, dear - out of memory - print an error message and exit
exit(1);
}
strncpy(new->word, newWord, WORD_SIZE); // Make sure not to overflow
// the buffer, so use strncpy
(new->word)[WORD_SIZE-1] = '\0'; // Make sure to zero terminate
new->freq = 1;
new->next = headPtr;
return new;
}
while(1)
{
int cmp = strcmp(current->word, newWord);
if(cmp == 0)
{
current->freq++;
return headPtr;
}
if(cmp < 0)
{
if ((current->next == NULL) || (strcmp(current->next->word, newWord) > 0))
{
// Add code to insert node after current
return headPtr;
}
}
else
{
// This should never happen...
printf("BAD CODE 1\n");
exit(1);
}
current = current->next;
}
}
关于c - 如何在链接列表中添加单词,同时检查和更新c中单词的频率,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/40918217/