Determine file/folder in C

问题

I have the following code in C:

DIR *mydir = opendir("/");
struct dirent *entry = NULL;

while((entry = readdir(mydir)))
{
    printf("%s\n", entry->d_name);
    //printf("%i\n", entry->d_type);
}

closedir(mydir);

It works and shows the files/folders in the location, correctly.

However, I want to tell if it is a folder or a file. How can I do this? I tried with d_type (as you can see on the code) but no success.

回答1:

Use stat():

struct stat st;
stat("nodename", &st);
int isDirectory = S_ISDIR(st.st_mode);

回答2:

You should use stat() function wich get you a stat structure.

struct stat s;
if( stat(path,&s) == 0 )
{
    if( s.st_mode & S_IFDIR )
    {
        //it's a directory
    }
    else if( s.st_mode & S_IFREG )
    {
        //it's a file
    }
    else
    {
        //something else
    }
}
else

{
    //error
}

回答3:

You can use built in macros like this:

#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>

int main(void)
{
  DIR *mydir = opendir(/);
  struct dirent *entry = NULL;
  struct stat buf;

  while((entry = readdir(mydir)))
  {
     printf("%s\n", entry->d_name);
     if (stat(entry, &buf))
     {
        perror("stat");
        exit(-1);
     }
     if ( S_ISDIR(buf.st_mode) ) 
     {
        printf("%s is a directory\n", entry);   
     }
     if ( S_ISREG(buf.st_mode) )
     {
        printf("%s is a regular file\n", entry);
     }
  }

  closedir(mydir);

  return 0;
}

See man 2 stat in a shell for more information.

回答4:

This is system-specific and we cannot give a completely solid answer without knowing your OS and possibly other settings.

d_type in fact does work for at least some systems. Your code gives a useful answer on RedHat Linux with a value of 4 for directories, 8 for regular files, and other values for other file types. This is with a fix to the typo to surround the name / in the call to opendir with quotes.

来源：https://stackoverflow.com/questions/13868994/determine-file-folder-in-c

标签

file