The routine CPXwriteparam writes the name and current setting of CPLEX parameters that are not at their default setting in the environment indicated by env.

This routine writes a file in a format suitable for reading by CPXreadcopyparam, so you can save current, nondefault parameter settings for re-use in a later session. The file extension is .prm. The PRM format is documented in the reference manual ILOG CPLEX File Formats.