Folder creation with C (mkdir)

c_mkdir_example.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h> 

//## include <sys/stat.h> required for mkdir
// gcc c_mkdir_example.c -o c_mkdir_example
// c_mkdir_example
// ls -l
main () {
  mkdir("Test_0777", 0777);
  //drwxrwsr-x 2 morganp morganp 4.0K Jun 16 18:10 Test_0777/
  
  mkdir("Test_777", 777);
  //dr----s--t 2 morganp morganp 4.0K Jun 16 18:10 Test_777
}

The leading '0' is very important in the file mode.