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c - 创建链表头的问题

问题描述

我的代码旨在从哈希链表中读取一系列字符串，将它们全部转换为小写，将它们放入一个数组中以对其使用快速排序，然后将它们放入一个称为字数的数据结构中，其中包括单词以及如何很多时候它出现在文档中。目前，当我运行代码时，它会使用我正在使用的打印语句正确打印出来，但是当我打印出来时，head 总是设置为 null。

这是 wordCount 声明：

typedef struct wordCount
{
    int count;
    char *word;
    struct wordCount* next;
} wordCount;

这是应该执行我上面描述的方法段。

else
    {
        char *toSort[curSize];
        int linkedListTraverse = 0; //Array index for each linked list node
        while(linkedList != NULL)
        {
            toSort[linkedListTraverse] = (char*) malloc(sizeof(linkedList->string));
            strcpy(toSort[linkedListTraverse],linkedList->string); //Copy the data from the linked list into an array 
            linkedList = linkedList->next;
            linkedListTraverse++;
        }
        int i = 0;
        while(i < curSize) //Convert all of the words to lowercase
        {
            char* str = toSort[i];
            char *p;
            for (p = str; *p != '\0'; p++)
                *p = (char)tolower(*p);
            i++;
        }
        i = 0;
        qsort(toSort, curSize, sizeof(char*), stringCmpFunc); //Sort the current node
        while(i < curSize)
        {
            printf("%s\n", toSort[i]);
            i++;
        }
        int curWordIndex = 0;
        int checkWordIndex = 1;
        wordCount *wordHead = NULL;
        wordCount *curWord = wordHead;
        while(curWordIndex < curSize)
        {
            curWord = (wordCount*) malloc(sizeof(wordCount));
            curWord->word = toSort[curWordIndex]; //Set the word
            curWord->count = 1; //Start the count out at 1
            while(strcmp(toSort[curWordIndex], toSort[checkWordIndex]) == 0) //While the two words are equal
            {
                checkWordIndex++; //Advance the leading index check
                curWord->count++;
                if(checkWordIndex >= curSize) //If the leading index goes beyond the array bounds
                    break;
            }
            if(checkWordIndex < curSize)
            {
                curWordIndex = checkWordIndex;
                checkWordIndex = curWordIndex + 1;
            }
            if(checkWordIndex >= curSize) //If the leading index goes beyond the array bounds
            {
                    if(strcmp(curWord->word, toSort[curWordIndex]) != 0)
                    {
                        printf("%s %d\n", curWord->word, curWord->count);
                        curWord = curWord->next;
                        curWord = (wordCount*) malloc(sizeof(wordCount));
                        curWord->word = toSort[curWordIndex]; //Set the word
                        curWord->count = 1; //Start the count out at 1
                    }
                    break;
            }
            //printf("CurWordIndex: %d\n CheckWordIndex: %d\n",curWordIndex, checkWordIndex);
            printf("%s %d\n", curWord->word, curWord->count);
            curWord = curWord->next; //Advance to the next node in the linked list
        }
        printf("%s %d\n", curWord->word, curWord->count);

这是只打印 null 的代码段

curWord = wordHead;
        while(curWord != NULL)
        {
            printf("%s %d\n", curWord->word, curWord->count);
            curWord = curWord->next;
        }

标签： clinked-listmalloc

解决方案

放

if (wordHead == NULL) { wordHead = curWord; }

后

curWord = (wordCount*) malloc(sizeof(wordCount));

更新

这是另一个问题：

curWord = curWord->next;
curWord = (wordCount*) malloc(sizeof(wordCount));

它应该是：

curWord->next = (wordCount*) malloc(sizeof(wordCount));
curWord = curWord->next;

注意：请遵守规则，这将有助于我们为您提供帮助。

更新/2

替换这个：

while(curWordIndex < curSize) {
    curWord = (wordCount*) malloc(sizeof(wordCount));

有了这个：

while(curWordIndex < curSize) {
    wordCount* tmp = (wordCount*) malloc(sizeof(wordCount));
    if (curWord) { curWord->next = tmp; }
    curWord =  tmp;

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