4.1.8 if statement

The synatax of the if statement is similar to its C counterpart. The Conditional Operator (ternary operator) has also been implemented.

     if(exp1)
        stmt1;
     else if(exp2)
        stmt2;
     else
        stmt3;
     
     # Can use code blocks as well:
     if(exp1){
        stmt1;
        stmt1a;
        stmt1b;
     } else if(exp2)
        stmt2;
     else {
        stmt3;
        stmt3a;
        stmt3b;
     }

For a variable or attribute expression to be logically true all its non-missing value elements must be logically true, i.e., non-zero. The expression can be of any type. Unlike C there is no short-circuiting of an expression with the OR (||) AND (&&) operators. The whole expression is evaluated regardless if one of the AND/OR operands are true/false.

     # Simple example
     if(time>0)
       print("All values of time are greater than zero\n");
     else if( time<0)
       print("All values of time are less than zero\n");
     else {
       time_max=time.max();
       time_min=time.min();
       print("min value of time=");print(time_min,"%f");
       print("max value of time=");print(time_max,"%f");
     }
     
     # Example from ddra.nco
     if(fl_typ==fl_typ_gcm){
       var_nbr_apx=32;
       lmn_nbr=1.0*var_nbr_apx*varsz_gcm_4D; /* [nbr] Variable size */
       if(nco_op_typ==nco_op_typ_avg){
         lmn_nbr_avg=1.0*var_nbr_apx*varsz_gcm_4D; /* [nbr] Averaging block size */
         lmn_nbr_wgt=dmnsz_gcm_lat; /* [nbr] Weight size */
       } // !nco_op_typ_avg
     }else if(fl_typ==fl_typ_stl){
       var_nbr_apx=8;
       lmn_nbr=1.0*var_nbr_apx*varsz_stl_2D; /* [nbr] Variable size */
       if(nco_op_typ==nco_op_typ_avg){
         lmn_nbr_avg=1.0*var_nbr_apx*varsz_stl_2D; /* [nbr] Averaging block size */
         lmn_nbr_wgt=dmnsz_stl_lat; /* [nbr] Weight size */
       } // !nco_op_typ_avg
     } // !fl_typ

Conditional Operator

     // netCDF4 needed for this example
     th_nw=(three_dmn_var_sht >= 0 ? three_dmn_var_sht.uint() : three_dmn_var_sht.int() );