C faster way to check if a directory exists

Question

I'm using opendir function to check if a directory exists. The problem is that I'm using it on a massive loop and it's inflating the ram used by my app.

What is the best (fastest) way to check if a directory exists in C? What is the best (fastest) way to create it if doesn't exists?

Answer 1

Consider using stat. S_ISDIR(s.st_mode) will tell you if it's a directory.

Sample:

#include <sys/types.h> #include <sys/stat.h> #include <unistd.h>  ... struct stat s; int err = stat("/path/to/possible_dir", &s); if(-1 == err) {     if(ENOENT == errno) {         /* does not exist */     } else {         perror("stat");         exit(1);     } } else {     if(S_ISDIR(s.st_mode)) {         /* it's a dir */     } else {         /* exists but is no dir */     } } ... 

Answer 2

You could call mkdir(). If the directory does not exist then it will be created and 0 will be returned. If the directory exists then -1 will be returned and errno will be set to EEXIST.