How to creating ctypes variables using python variables instead of hard-coded values?

How to creating ctypes variables using python variables instead of
hard-coded values?

When creating ctypes variables, can one not pass values using python
variables?
I have some code where I am calling a shared C library. If I pass the
parameters to this C library using Method 1 (see below) things work well.
But if I use Method 2, I get garbage. There are other parts to the code.
But I have confirmed that when I replace Method 2 with Method 1, things
work well. So something is wrong here.
If what I am doing in Method 2 is not valid, what is the alternative if I
want to automate the process of running the code for different values of a
given variable(s)?
Method 1 (This works well)
import ctypes as C
c_thresholds = (C.c_double * 4)()
for idx, value in enumerate(thresholds):
c_thresholds[idx] = value
goodH = Good(C.c_char('H'), C.c_double(0.5), C.c_int(100), C.c_int(20))
goodL = Good(C.c_char('L'), C.c_double(0.5), C.c_int(75), C.c_int(20))
c_parameters = Params(
var1 = C.c_int(100),
var2 = C.c_int(4),
var3 = C.c_int(5),
var4 = C.c_int(5000),
var5 = C.c_char_p("modelname"),
var6 = C.c_double(0.5),
var7 = C.c_double(90),
var8 = c_thresholds,
var9 = C.c_int(2),
H = goodH,
L = goodL
)
runsimulation(c_parameters)
Method 2 (This does not work, outputs garbage)
import ctypes as C
def create_cparams(var1, var2, var3, var4, var5, var6, var7, var8, var9):
c_thresholds = (C.c_double * 4)()
for idx, value in enumerate(var8):
c_thresholds[idx] = value
goodH = Good(C.c_char('H'), C.c_double(0.5), C.c_int(100), C.c_int(20))
goodL = Good(C.c_char('L'), C.c_double(0.5), C.c_int(75), C.c_int(20))
c_parameters = Params(
var1 = C.c_int(var1),
var2 = C.c_int(var2),
var3 = C.c_int(var3),
var4 = C.c_int(var4),
var5 = C.c_char_p(var5),
var6 = C.c_double(var6),
var7 = C.c_double(var7),
var8 = c_thresholds,
var9 = C.c_int(var9),
H = goodH,
L = goodL
)
return c_parameters
# These are python variables
var1 = 100
var2 = 4
var3 = 5
var4 = 5000
var5 = "modelname"
var6 = 0.5
var7 = 90
var8 = [1, 0.9, 0.8, 0.7]
var9 = 2
# Calling the create_cparams function defined above
c_parameters = create_cparams(var1, var2, var3, var4, var5, var6, var7,
var8, var9)
runsimulation(c_parameters)
In case it is helpful the Params class is given by (does not change across
the two methods):
class Params(C.Structure):
_fields_ = [
("var1", C.c_int),
("var2", C.c_int),
("var3", C.c_int),
("var4", C.c_int),
("var5", C.c_char_p ),
("var6", C.c_double),
("var7", C.c_double),
("var8", (C.c_double * 4) ),
("var9", C.c_int),
("H", Good),
("L", Good)
]