Comparing Index-Names and Index Data Items

Comparisons involving index-names and/or index data items conform to the following rules:
  • The comparison of two index-names is a comparison of the corresponding occurrence numbers.
  • In the comparison of an index-name with a data item (other than an index data item), or in the comparison of an index-name with a literal, the occurrence number of the index-name is compared with the data item or literal.
  • IBM Extension
    IBM Extension In the comparison of an index-name with an arithmetic expression, the occurrence number that corresponds to the value of the index-name is compared with the arithmetic expression.

    Since an integer function may be used wherever an arithmetic expression may be used, this extension allows you to compare an index-name to an integer or numeric function.

    End of IBM Extension
    End of IBM Extension
  • In the comparison of an index data item with an index-name or another index data item, the actual values are compared without conversion. Results of any other comparison involving an index data item are undefined.

Table 1 shows valid comparisons involving index-names and index data items.

Table 1. Comparisons Involving Index Names and Index Data Items
Operands Compared Index-Name Index Data Item Data-Name Literal Arithmetic Expression
Index-Name Compare occurrence number Compare without conversion Compare occurrence number with data-name Compare occurrence number with literal Compare occurrence number with arithmetic expression
Index Data Item Compare without conversion Compare without conversion Not permitted Not permitted Not permitted