I'm using a curve modifier and an array modifier. My object is at one end of the curve but as soon as I choose the curve for the curve modifier it moves to the center. How can I fix the problem so that I can have the array going from one end of the curve to the other?
Make sure both your object center and curve center positions in the scene are exactly the same before using the modifier.
Also helps some times if the first curve vertex is exactly at the curve center (local coordinate [0,0,0] ), or ideally ata the start vertex of the curve.
Make sure both your object and curve have applied scales [1,1,1] in every axis. If it is not and you apply the scale make sure afterwards the curve radius is reset to zero. Do so by entering Edit Mode, selecting all vertex, right-clicking and pressing Set Curve Radius.
Also ensure both objects have matching rotations.
If you still get unexpected results try inverting the curve direction in Edit Mode by selecting one of its vertex and pressing the Revert button in the 3DView Tool shelf, or right-clicking it and pressing Switch Direction from the context menu.