how to determine directory or file in linux in c

I want to print only file names without printing Directory Names. So, I implement this function

void list_file(char* directory){
  DIR *d;
  struct dirent *dir;
  d = opendir(directory);
  if (d)
  {
    while ((dir = readdir(d)) != NULL)
    {
        printf("%c", dir->d_name[(int)strlen(dir->d_name)]);
        if(dir->d_name[(int)strlen(dir->d_name)-2] != '/')
            printf("%sn", dir->d_name);
    }

    closedir(d);
  }
}

I checked that Directory names ends with ‘/’ character. So, I checked that if there are ‘/’ character at the end of name, don’t print that name but when I run the function, all of them is printed in selected directory?

Can you lead me that how can I check the end of Directory name?

Answer

What you are looking for is stat or one of its variants. Specifically look at the st_mode field of struct stat. The macro you are interested in is S_ISDIR(x).

Find below your modified code that demonstrates what you want:

void list_file(char* directory) {
  DIR *d;
  struct dirent *dir;
  int dir_len = strlen(directory);
  char* path = malloc(dir_len + NAME_MAX + 2); // +2, 1 for '/' and 1 for ''
  if(path == NULL) {
    fprintf(stderr, "malloc failedn");
    return;
  }
  strcpy(path, directory);
  if(path[dir_len-1] != '/') {
    path[dir_len] = '/';
    dir_len++;
  }
  d = opendir(directory);
  if (d) {
    while ((dir = readdir(d)) != NULL)
    {
      struct stat buf;
      strcpy(&path[dir_len], dir->d_name);
      if(stat(path, &buf) < 0) {
        fprintf(stderr, "errorn");
      }
      else {if(!S_ISDIR(buf.st_mode)) {
          printf("%sn", dir->d_name);
        }
      }
    }

    closedir(d);
  }
  free(path);
}

I have removed your first print as it was printing the null terminating character of the string.

Update:

As pointed out in the comments since we are dealing with Linux you can use the d_type field in struct dirent (which is not part of POSIX but is part of Linux).

With that said the code would be the following.

void list_file(char* directory){
  DIR *d;
  struct dirent *dir;

  d = opendir(directory);
  if (d) {
    while ((dir = readdir(d)) != NULL)
    {
      struct stat buf;
      if(dir->d_type == DT_DIR) {
         printf("%sn", dir->d_name);
      }
    }

    closedir(d);
  }
}

It is a lot cleaner, no need for malloc.