IF OPERATOR

This operator can select one of two alternative branches according to the result of some logical expression analyses.

Reserved words IF, THEN and ELSE of conditional operator put bounds to analysing logic expression and two operators, which are selected in dependence if expression TRUE or FALSE.

Typical examples of conditional operator, available in "COMPAS":

• IF a = 1 THEN s:=1 ELSE s:=0;
• IF a = 1 THEN s:=1;
• IF a = 1 THEN BEGIN s:=1; q:=s+1 END ELSE BEGIN s:=0; q:=0 END;
• IF c < ' ' THEN c:=CHR(0);
• IF b THEN w:=w-1;

Possible structures of this operator can be written the following way:

IF {condition} THEN {operator1} ELSE {operator2} ;

IF {condition} THEN {operator1} ;

IF {BOOLEAN variable} THEN {operator1} ELSE {operator2} ;

IF {BOOLEAN variable} THEN {operator1} ;