c - 在 C 中传递字符串

Question

我正在实现一个绳索数据结构。如何传递我的字符串值？它们显示为“(null)”。我认为我的字符字设置不正确。我是 C 新手，来自 C++。这最终将成为一个文本编辑器，但现在我只是尝试按索引号在有序列表中显示输入的字符串。

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

typedef struct treeNode
{
    int i, length; 
    char word;
    struct treeNode *left;
    struct treeNode *right;
} treeNode;

treeNode *insert(treeNode *node, int i, char word, int length)
{
    printf("Insert %d :", word);
    if(node==NULL)
    {
        treeNode *temp;
        temp = (treeNode *)malloc(sizeof(treeNode));
        temp->i = i;
        temp->word;
        temp->length;
        temp->left = temp->right = NULL;
        return temp;
    }

    if(i >(node->i))
        node->right = insert(node->right, i, word, length);

    else if(i < (node->i))
        node->left = insert(node->left,i,word,length);
    return node;
}

void PrintInorder(treeNode *node)
{
    if(node==NULL)
        return;
    PrintInorder(node->left);
    printf("%d", node->i);
    printf("%s", node->word);
    PrintInorder(node->right);
}

void main()
{
    treeNode *root = NULL;
    char word[256];
    int length, a;
    for(a = 0; a < 3; a++)
    {
        printf("Enter word: ");
        scanf("%s", word);
        length = strlen(word);      
        root = insert(root, a, *word,length);
    }
    printf("Print in order:\n");  
    PrintInorder(root);
}

Answer 1

您需要在 treeNode 中使用 char *word 来表示一个字符串(一段绳子)。您需要使用 char *word 定义 insert，并使用 word 调用它，而不是 *word (因为在调用上下文，这将是 word 的第一个字符)。最后，您实际上需要一些分配:temp->word = word。

代码中还有其他逻辑错误，特别是没有以任何重要方式处理 i 或 length，但它们至少不会阻止您按顺序打印.

编辑:

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

typedef struct treeNode
{
    int i, length; 
    //char word;                // this only stores a single character
    char *word;               // needs to be a pointer so it can point to string
    struct treeNode *left;
    struct treeNode *right;
}treeNode;

// this accepts a single character as `word`, not a string
// treeNode *insert(treeNode *node, int i, char word, int length){
// needs to be `*word`
treeNode *insert(treeNode *node, int i, char *word, int length)
{
    printf("Insert %d :",word );
    if(node==NULL)
    {
        treeNode *temp;
        temp = (treeNode *)malloc(sizeof(treeNode));
        temp->i = i;
        // temp->word;           // This does nothing;
        temp->word = word;    // This assigns the pointer
        temp->length;
        temp->left = temp->right = NULL;
        return temp;
    }

    // This logic does not work correctly... What is `i` specifically?
    if(i >(node->i))
        node->right = insert(node->right,i,word,length); // OK because passing pointer

    else if(i < (node->i))
        node->left = insert(node->left,i,word,length); // OK because passing pointer
    return node;
}

void PrintInorder(treeNode *node)
{
    if(node==NULL)
         return;
    PrintInorder(node->left);
    printf("%d",node->i);
    printf("%s",node->word);
    PrintInorder(node->right);
}

void main()
{
    treeNode *root = NULL;
    char word[256];
    int length, a;
    for(a = 0; a < 3; a++)
    {
        printf("Enter word: ");
        scanf("%s", word);
        length = strlen(word);      
        // root = insert(root, a, *word,length); // This would only pass the first character of `word`
        root = insert(root, a, word,length);  // We want to pass the word pointer
    }
    printf("Print in order:\n");  
    PrintInorder(root);
}