Question

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <dirent.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>
#include <sys/stat.h>

struct node
{
    char *s_xmlfile;
    char *s_file_mod_time;
    struct node *link;
};

struct node* head = NULL;

int table(char *);
struct node *getnode();
void readnode(struct node *, char *, char *);
void add_table(struct node **, char *);
void delete_node(struct node**);
void display(struct node *);
char* modification( char*);
const char *getExt (const char *);
void scan_directory (char *);
char* modified_time(char *);

int main(int argc, char *argv[])
{
    printf("\n");
    scan_directory(argv[1]); //enter the directory full path from command line
    display(head);
    return 0;
}

/***scan directory and get all files**/
void scan_directory (char *dir_location)
{
    DIR *dir_ptr;
    struct dirent *file_ptr;     
    chdir(dir_location);
    dir_ptr = opendir (dir_location);
    int dir_len = strlen(dir_location);
    if (dir_ptr != NULL){
        while (file_ptr = readdir (dir_ptr)){
                if( !strcmp((getExt (file_ptr->d_name)), ".xml") ){
                table(file_ptr->d_name);
            }
        }

        (void) closedir (dir_ptr);
    }
    else
        perror ("Couldn't open the directory");

}

/**load only xml file**/
const char *getExt (const char *fspec) 
{
    char *e = strrchr (fspec, '.');
        if (e == NULL)
            e = "";
    return e;
}

/**creating a table to store xml files and
   last file modified time using linked list**/
int table(char *xml_file)
{
    add_table(&head, xml_file);
    //display(head);
}

void add_table(struct node **headptr, char *xml_file)
{
    char *mod_time;
    struct node *loc_head, *last, *newnode;
    loc_head = *headptr;

    mod_time = modified_time(xml_file);
    printf("TIME : %s FILE : %s\n", mod_time, xml_file);
    newnode = getnode();

    newnode -> s_xmlfile = xml_file;
    newnode -> s_file_mod_time = mod_time; 
    newnode -> link = NULL;

    if(loc_head == NULL){
        printf("Debug: Empty table \n");
        loc_head = newnode;
    }
    else{
        last = loc_head;
        while(last ->link != NULL){
        last = last -> link;}
        last->link = newnode;
    }
    *headptr = loc_head;
}

struct node *getnode()
{
    struct node *newnode;
    newnode = (struct node*)malloc(sizeof(struct node));
    return (newnode);
}

void display(struct node *q)
{
    printf("\nDISPLAY\n");
        if(q==NULL){
        //printf("\nEmpty Table.");
        return;
        }
        while(q!=NULL){
        printf("%s\t", q -> s_xmlfile);
        printf("%s\n", q -> s_file_mod_time);
        q=q->link;
        }
    printf("\n");
}

/**identifying last modified time of file**/
char* modified_time(char *xml_file)
{
    struct stat sb;
    char *temp_time;;
    if(stat(xml_file, &sb) == -1)
            perror("stat");
    temp_time = ctime(&sb.st_mtime);
    return temp_time;
}

实际问题是链接列表中所有时间字段的最后文件时间更新

描述：该程序将扫描目录中的xml文件，并获取xml文件的最后更新时间，然后进入链表。

实际o / p：

TIME : Mon Jan 28 22:29:42 2013
 FILE : HLM2.xml
Debug: Empty table
TIME : Mon Jan 28 17:41:28 2013
 FILE : HLM1.xml
TIME : Thu Jan 31 22:57:36 2013
 FILE : HLM3.xml

DISPLAY
HLM2.xml    Thu Jan 31 22:57:36 2013

HLM1.xml    Thu Jan 31 22:57:36 2013

HLM3.xml    Thu Jan 31 22:57:36 2013

预期o / p：

TIME : Mon Jan 28 22:29:42 2013
FILE : HLM2.xml
Debug: Empty table
TIME : Mon Jan 28 17:41:28 2013
 FILE : HLM1.xml
TIME : Thu Jan 31 22:57:36 2013
 FILE : HLM3.xml

DISPLAY
HLM2.xml    Thu Jan 31 22:57:36 2013

HLM1.xml    Mon Jan 28 17:41:28 2013

HLM3.xml    Thu Jan 31 22:57:36 2013

diretory我给出了3个xml文件我的链接列表程序有任何错误。

Answer 1

这是经典的“让我们指出一个指向本地字符数组的指针”问题。

而不是：

newnode -> s_xmlfile = xml_file;

你需要：

newnode -> s_xmlfile = strdup(xml_file);

或：

int len = strlen(xmlfile);
char *name = malloc(len+1);
strcpy(name, xmlfile);
newnode -> s_xmlfile = name;

最后清理时不要忘记释放newnode->s_xmlfile。

或者s_xmlfile进入char s_xmlfgile[MAX_FILE_NAME_SIZE]而strcpy(newnode->s_xmlfile, xmlfile); - 确保MAX_FILE_NAME_SIZE足够大。

链接列表中所有节点的最后一个节点值更新

1 个答案: