IF and CASE — the statements

Level: 101 · newcomer

Status: stub — the shape is here; the worked program is not yet.

One line: IF/ELSEIF/ELSE tests conditions and CASE/WHEN compares one operand against values, exactly as elsewhere — the ABAP-specific parts are the word operators (IS INITIAL, IS BOUND, IS ASSIGNED, BETWEEN, CO, CS) and the fact that CASE cannot express a range.

What it does

IF lv_amount > 0 AND lo_handler IS BOUND.
ELSEIF lv_amount IS INITIAL.
ELSE.
ENDIF.

CASE lv_status.
  WHEN 'A' OR 'B'.
  WHEN OTHERS.
ENDCASE.

CASE … WHEN OTHERS is not required, and leaving it out is how an unexpected status does nothing at all rather than being reported. WHEN TYPE lcl_thing (7.02+) branches on an object's class, which is occasionally the right tool and usually a sign that the class hierarchy is missing a method.

The operators worth knowing

IS INITIAL (the value is its type's initial value — not null, ABAP has no null), IS BOUND (a reference points at something), IS ASSIGNED (a field symbol points at something), IS SUPPLIED (an optional parameter was actually passed), BETWEEN a AND b, and the character-comparison family CO, CN, CA, NA, CS, NS, CP, NP — of which CS (contains string) and CP (covers pattern, with * and +) are the two that earn their keep.

What this page still needs

• [ ] a snippets/ program exercising IS INITIAL against IS BOUND against IS ASSIGNED
• [ ] the CO/CA/CS family with a worked example each, and sy-fdpos
• [ ] when CASE TYPE OF is right and when it is a missing method

See also

• COND and SWITCH — the same two choices as expressions
• CHECK, CONTINUE, EXIT, RETURN — leaving early instead of nesting
• FIELD-SYMBOLS and ASSIGN — why IS ASSIGNED is a different question from IS INITIAL
• CASE TYPE OF — branching on an object's class, and when not to
• Booleans — xsdbool( ), boolc( ), and why there is no boolean type