Three types of set parameters are supported: INTEGER, REAL, and STRINGn.

INTEGER

If you want to sum up all the elements in a set of integers with an external function, to declare the function in the SERVICE structure:

  SetFuncLib := SERVICE
    INTEGER SumInt(SET OF INTEGER ss) :
       holertl,library='dab',entrypoint='rtlSumInt';
  END;
  x:= 3+4.5;
  SetFuncLib.SumInt([x, 11.79]); //passed two REAL numbers - it works

To define the external function, in the header (.h) file:

__int64 rtlSumInt(unsigned len, __int64 * a);

In the source code (.cpp) file:

  __int64 rtlSumInt(unsigned len, __int64 * a) {
       __int64 sum = 0;
       for(unsigned i = 0; i < len; i++) {
            sum += a[i];
       }
       return sum;
    }

The first parameter contains the length of the set, and the second parameter is an int array that holds the elements of the set. Note: In declaring the function in ECL, you can also have sets of INTEGER4, INTEGER2 and INTEGER1, but you need to change the type of the C function parameter, too. The relationship is:

  INTEGER8 -- __int64
  INTEGER4 -- int
  INTEGER2 -- short
  INTEGER1 -- char

REAL

If you want to sum up all the elements in a set of real numbers:

To declare the function in the SERVICE structure:

  SetFuncLib := SERVICE
       REAL8 SumReal(SET OF REAL8 ss) :
            holertl,library='dab',entrypoint='rtlSumReal';
  END;
  
  INTEGER r1 := 10;
  r2 := 20.345;
  SetFuncLib.SumReal([r1, r2]);
  // intentionally passed an integer to the real set, it works too.

To define the external function, in the header (.h) file:

double rtlSumReal(unsigned len, double * a);

In the source code (.cpp) file:

  double rtlSumReal(unsigned len, double * a) {
    double sum = 0;
    for(unsigned i = 0; i < len; i++) {
       sum += a[i];
    }
    return sum;
  }

The first parameter contains the length of the set, and the second parameter is an array that holds the elements of the set.

Note: You can also declare the function in ECL as set of REAL4, but you need to change the parameter of the C function to float.

STRINGn

If you want to calculate the sum of the lengths of all the strings in a set, with the trailing blanks trimmed off:

To declare the function in the SERVICE structure:

  SetFuncLib := SERVICE
    INTEGER SumCharLen(SET OF STRING20 ss) :
       holertl,library='dab',entrypoint='rtlSumCharLen';
  END;
  str1 := '1234567890'+'xxxx ';
  str2 := 'abc';
  SetFuncLib.SumCharLen([str1, str2]);

To define the external function, in the header (.h) file:

__int64 rtlSumCharLen(unsigned len, char a[ ][20]);

In the source code (.cpp) file:

__int64 rtlSumCharLen(unsigned len, char a[][20]) {
    __int64 sumtrimedlen = 0;
       for(unsigned i = 0; i < len; i++) {
          for(int j = 20-1; j >= 0; j--) {
            if(a[i][j] != ' ') {
              break;
            }
            a[i][j] = 0;
       }
       sumtrimedlen += j + 1;
    }
    return sumtrimedlen;
  } 

Note: In declaring the C function, we have two parameters for the set. The first parameter is the length of the set, the second parameter is char[][n] where n is the SAME as that in stringn. Eg., if the service is declared as "integer SumCharLen(set of string20)", then in the C function the parameter type must be char a[][20].