export field variable to text file
 

how to export field variables of the a part of a computational domain for example if i have a 1m X 1m slab i want all the filed variables such as pressure velocity and temperatures for the grid points or cells for which x-coordinates is greater than 0.25 m and less than 0.75m and y-coordinates is greater than 0.5m and less than 0.6m. if i have to write a UDF for that please guide me. i want the data in a tabular format like

X-coordinate Y-coordinate Z-coordinate(for 3D) Pressure U-vel V-vel W-vel Temp.

please help me....