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FOR - Iteration Expressions

Other versions: 7.31 | 7.40 | 7.54

Syntax

... REDUCE|
NEW|
VALUE type( ... FOR ... UNTIL|WHILE ...|
... IN ... ... ) ...

Effect

The language element FOR introduces an iteration expression as a subexpression in constructor expressions with the reduction operator REDUCE and in the variants of the instance operator NEW and the value operator VALUE for creating internal tables.

There are two main variants of iteration expressions:

• Iteration expressions with UNTIL or WHILE for conditional iterations. These expressions are used to create (iteratively) the results of any data types using REDUCE or to create rows of internal tables using NEW or VALUE. The iteration steps can be defined as required.

• Iteration expressions with IN for table iterations. These expressions are used for table reductions using REDUCE or table comprehensions using NEW or VALUE. The iteration steps here evaluate an existing internal table.

Notes

• Any FOR variants can be combined in a single constructor expression, where they produce nested iterations.

• The reduction operator REDUCE must contain at least one iteration expression. The variants of the instance operator NEW and the value operator VALUE for creating internal tables can contain iteration expressions.

• The conditional iterations using UNTIL or WHILE provide an expression-oriented alternative to the loop statements DO and WHILE. The same applies to the table iterations using IN and the statement LOOP. The direct use of operand positions by the expression-oriented variants helps to avoid using helper variables. Furthermore, they also enable certain tasks, such as creating values iteratively, to be expressed more concisely and more elegantly.

Continue

FOR - Conditional Iteration

Examples of Iteration Expressions