Update: cpp example package to use cpp stdlib. (#2)

Uses std:vector and std:algorithm to check that
the cpp standard library is linked and called
correctly.

Author: LKedward

example_packages/cpp_files/src/cpp_files.f90

@@ -3,10 +3,12 @@ module cpp_files
   implicit none
   private
 
-  public :: hello_world
+  public :: intvec_maxval
 
   interface
-    subroutine hello_world() bind(C, name = "hello_world")
-    end subroutine hello_world
+    integer function intvec_maxval(array, n) bind(C, name = "intvec_maxval")
+      integer, intent(in) :: array(*)
+      integer, intent(in), value :: n
+    end function intvec_maxval
   end interface
 end module cpp_files

example_packages/cpp_files/src/hello_world.cpp

@@ -1,9 +1,14 @@
-#include <iostream>
+#include <vector>
+#include <algorithm>
 
 extern "C" {
-  int hello_world();
-}
 
-int hello_world() {
-    std::cout << "Hello World";
+int intvec_maxval(int* array, size_t n){
+
+  std::vector<int> vec(array, array + n);
+  
+  return *(std::max_element(vec.begin(), vec.end()));
+  
 }
+
+}

example_packages/cpp_files/test/check.f90

@@ -1,5 +1,17 @@
 program check
-implicit none
+  use cpp_files
+  implicit none
+
+  integer :: i, max_element
+  integer, parameter :: array(*) = [(i,i=-50,10)]
+  
+  max_element = intvec_maxval(array,size(array,1))
+
+  if (max_element == maxval(array)) then
+    write(*,*) ' PASSED: Max element is ',max_element
+  else
+    write(*,*) ' (!) FAILED: Incorrect max element returned'
+    stop 1
+  end if
 
-print *, "Put some tests in here!"
 end program check