Function SCIPchgVarType 

pub unsafe extern "C" fn SCIPchgVarType(
    scip: *mut SCIP,
    var: *mut SCIP_VAR,
    vartype: SCIP_VARTYPE,
    infeasible: *mut c_uint,
) -> SCIP_RETCODE

changes type of variable in the problem;

@warning This type change might change the variable array returned from SCIPgetVars() and SCIPgetVarsData();

@return \ref SCIP_OKAY is returned if everything worked. Otherwise a suitable error code is passed. See \ref SCIP_Retcode “SCIP_RETCODE” for a complete list of error codes.

@pre This method can be called if @p scip is in one of the following stages: - \ref SCIP_STAGE_PROBLEM - \ref SCIP_STAGE_TRANSFORMING - \ref SCIP_STAGE_PRESOLVING

@note If SCIP is already beyond the SCIP_STAGE_PROBLEM and a original variable is passed, the variable type of the corresponding transformed variable is changed; the type of the original variable does not change

@note If the type changes from a continuous variable to a non-continuous variable the bounds of the variable get adjusted w.r.t. to integrality information