Detailed example working with gfortran/g++ mixed compilation, but without module

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>

wrappers/Fortran/detailed_example/README.md

@@ -0,0 +1,27 @@
+FORTRAN example without module
+==============================
+
+To build static library
+-----------------------
+
+Start in root folder of repo
+
+    mkdir build
+    cd build
+    mkdir gccstatic
+    cd gccstatic
+    cmake ../.. -G "MinGW Makefiles" -DCOOLPROP_STATIC_LIBRARY=ON
+    cmake --build .
+
+This will generate the file libCoolProp.a which is a GCC static library that can be linked with GCC/GFORTRAN code
+
+Make sure that the macro COOLPROP_LIB is defined and that the macro CONVENTION=__cdecl is set.
+
+Copy this .a file into the directory with the coolprop FORTRAN example
+
+To build FORTRAN example
+------------------------
+
+    gfortran -c cool_fortran_bind.f90
+    gfortran libCoolProp.a cool_fortran_bind.f90 -o main -lstdc++
+    main

wrappers/Fortran/detailed_example/cool_fortran_bind.f90

@@ -0,0 +1,69 @@
+program hello
+
+    !Use TestData       ! Include a Module with the interface, Optional (to not re-write the Interface every at Subroutine or Program)
+    
+    use iso_c_binding
+    implicit none 
+
+!The interface to use the PropsSI Function
+INTERFACE
+     FUNCTION PropsSI  &
+        (output, name1, prop1, name2, prop2, fluidname)    &
+            BIND(C, NAME='PropsSI')
+        use iso_c_binding
+        real(C_DOUBLE) :: PropsSI
+	    character(KIND=c_char) :: output(*)
+	    character(c_char) :: name1(*)
+	    real(C_DOUBLE), VALUE :: prop1
+	    character(c_char) :: name2(*)
+	    real(C_DOUBLE), VALUE :: prop2
+	    character(kind=c_char) :: fluidname(*)
+            
+    END FUNCTION PropsSI
+   
+END INTERFACE
+
+
+!Here Start the programa
+
+
+!Initializate the variables used in the example
+   !implicit none   
+double precision T,Q,D,h,s
+character(LEN=32) fluid, PropName
+character(LEN=32) out1, n1, n2
+double precision dens1, dens2, prop1, prop2
+
+
+!----------------------
+!Example calculates: (Example Code for MATLAB)
+!
+!Density of saturated liquid Propane at 300 K:
+!---------------------
+
+  
+T = 300                 ! Defining the temperature
+Q = 0                   ! Defining the quality
+!D = 1250;
+
+
+out1 = "D"//CHAR(0)      ! String with of the output Propertie   
+n1  = "T"//CHAR(0)       ! String with of the input Propertie #1
+n2  = "Q"//CHAR(0)       ! String with of the input Propertie #2
+fluid    = "Propane"//CHAR(0)   ! String with the fluid name
+
+ 
+! From the CoolProp 4.2.1 documentation ->> CoolProp.CoolProp.Props
+! Call Type #2:
+!   Props(OutputName,InputName1,InputProp1,InputName2,InputProp2,Fluid) --> float
+!
+  
+dens1 = PropsSI(out1, n1, T, n2, Q, fluid)                                !calling props, strings are Variables
+  
+dens2 = PropsSI("D"//CHAR(0), "T"//CHAR(0), T, "Q"//CHAR(0), Q, fluid)    !calling props deffinig the strings directlly in the arguments 
+
+
+Print *, dens1
+  
+
+end program hello