有问题分配字符串指针字符串值

Having problems assigning character string pointer string value

本文关键字:字符串 指针 有问题 分配      更新时间:2023-10-16

我有问题分配ptr->str令牌值。不确定ptr->str是指向char的指针,所以是token。printf不打印字符值。我得到一个运行时错误。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include "C2A6E4_List-Driver.h"
typedef struct List
{
    struct List *next;   /* pointer to the next list node */
    char *str;           /* pointer to the string represented */
    int count;           /* # of occurrences of this string */
} List;
#endif

#define LINESIZE 256
#define DELIMETERS " "
typedef enum { false, true }bool;
List *newNode(void);
bool searchNode(List *head, char *key);
List *CreateList(FILE *fp)
{
    List *head, *ptr;
    int cnt = 0;
    size_t length;
    bool firstNode = true;
    bool srchResult = false;
    char buf[LINESIZE];
    while (fgets(buf, (int)sizeof(buf), fp) != NULL) { /* read line of file*/
        char *token = strtok(buf, DELIMETERS);
        while (token != NULL) {
            if (firstNode) {
                ptr = newNode();
                length = strlen(token) + 1;
                //  ptr->str = (char *)malloc(sizeof(char) * length);
                ptr->next = head;
                ptr->str = token;
                ptr->count = 1;
                head = ptr;
                firstNode = false;
            }
            else {
                srchResult = searchNode(head, token);
                printf("srchResult= %dn", srchResult);
                if (srchResult) {
                    ptr = newNode();
                    length = strlen(token) + 1;
                    ptr->next = head;
                    ptr->str = token;
                    printf("ptr_str = %s", ptr->str);
                    ptr->count += 1;
                    head = ptr;
                }//end if
            }
            printf("token = %sn", token);
            token = strtok(NULL, DELIMETERS);
        }//end while
    }// end while fgets
    return head;
}

List *newNode(void)
{
    List *ptr = (List *)malloc(sizeof(List));
    if (ptr == NULL) {
        fputs("Out of Memoryn ", stderr);
        exit(EXIT_FAILURE);
    }
    return ptr;
}

bool searchNode(List *head, char *key)
{
    List *cur = head;
    bool cmpResult = false;
    printf("key = %sn", key);
    while (cur) {
        printf("call strmcmpn");
        printf("cur->str = n", cur->str);
        cmpResult = strcmp(cur->str, key);
        printf("cmpResult = %dn", cmpResult);
        if (cmpResult == 0) {
            return false;
            cur->count += 1;
        }
        cur = cur->next;
        printf("curnextn");
    }
    if (cmpResult > 0 || cmpResult < 0)
        cmpResult = true;
    printf("returnn");
    return cmpResult;
}

List *PrintList(const List *head)
{
    List *cur = head;
    while (cur) {
        printf(" %s  %d   ean", cur->str, cur->count);
        cur = cur->next;
    }
    return (List *)head;
}

void FreeList(List *head)
{
    List *cur = head, *tmp;
    while (cur) {
        tmp = head;
        head = head->next;
        free(tmp);
    }
}

变量'head'没有在createNode中初始化,因此,当您稍后在searchNode或PrintList中遍历树时,在'ptr->next'中替换head可能会导致意外行为。