c# - Counting an Array XNA HLSL -

wondering how count array in hsls? say, have array declared in our effect file:

float2 position[1]; 

and inside our source set parameter else instance:

effect.parameter["position"].setvalue(myvector2array); 

under shadering function how count array? similar to:

float4 ps_function(float2 tex : texcoord0) : color0 { int size = position.count(); } 

thanks in advance :]

the simple way declare constant define array size:

const static int max_positions = 1 float2 position[max_positions];