add example

Author: perazz

example/system/CMakeLists.txt

@@ -1,4 +1,5 @@
 ADD_EXAMPLE(get_runtime_os)
+ADD_EXAMPLE(is_directory)
 ADD_EXAMPLE(os_type)
 ADD_EXAMPLE(process_1)
 ADD_EXAMPLE(process_2)

example/system/example_is_directory.f90

@@ -0,0 +1,11 @@
+! Demonstrate usage of `is_directory`
+program example_is_directory
+  use stdlib_system, only: is_directory
+  implicit none
+  ! Test a directory path
+  if (is_directory("/path/to/check")) then 
+    print *, "The specified path is a directory."
+  else
+    print *, "The specified path is not a directory."
+  end if
+end program example_is_directory