read only .txt files from directory which has subfolders too

I am trying to read only .txt files from directory. I am not using arrays. I am using opendir() to open my directory. d->d_name lists all my files and also subfolders. I want to read only .txt but not the subfolders.

please help m开发者_运维百科e. Thanks

Can you not use FindFirstFile and FindNextFile for this?

Well, something like:

• call opendir() to open the directory
• in a loop, call readdir to read each entry
• for each entry, examine the name to see if the last 4 characters are ".txt"
• if they are, do something
• at the end, call closedir to close the directory

You can use the stat() function to determine the type of file your struct dirent represents.

struct stat sb;
int rc = stat(filename, &sb);
// error handling if stat failed
if (S_ISREG(sb.st_mode)) {
 // it's a regular file, process it
} else {
 // it's not a regular file, skip it
}

Read the man pages for details. Also take care that the filename in d_name does not contain the directory part. If you're in a different directory than what you opendir'd, you'll need to prepend the directory name (and a directory separator if required).

For a C++ alternative, please see boost::filesystem.

You could try put the filenames into a simple structure (string array or vector for example), then pass a reference to that structure to a function that prunes names that don't use the .txt extension

in the function, look at each filename (a for loop would be handy), and use the find function in the String library to see if the last four characters are == to .txt. You can reset the position of to start searching the string to string_name.length - 4 so that you're only comparing the last few characters.

Cplusplus.com is a great reference for things like the String library: http://www.cplusplus.com/reference/string/string/find/

Assuming you are on a Linux/Posix system, you can use scandir(...). You can find the details on the manual page, but in short, you have to provide a filter function that takes a dirent pointer as argument, and returns non-zero if the entry is to be included (in your case, you would check for the name ending in .txt, and possibly the file type in the dirent struct).

#include <stdio.h>
#include <sys/types.h>
#include <dirent.h>
#include <errno.h>

int main(int argc, char *argv[])
{
    DIR *dir;

    struct dirent *entry;

    int pos;

    if (argc < 2)
    {
        printf("Usage: %s <directory>\n", argv[0]);
        return 1;
    }

    if ((dir = opendir(argv[1])) == NULL)
    {
        perror("opendir");
        return 1;
    }

    while ((entry = readdir(dir)) != NULL)
    {
        if (entry->d_type != DT_REG)
            continue;

        pos = strlen(entry->d_name) - 4;

        if (! strcmp(&entry->d_name[pos], ".txt"))
        {
            printf("%s\n", entry->d_name);
        }
    }

    if (closedir(dir) == -1)
    {
        perror("closedir");
        return 1;
    }

    return 0;
}