IF (e) s1,s2,s3

e Is an arithmetic expression.

s1,s2,s3 Are labels of executable statements in the same program unit. All three labels are required, but they need not refer to different statements.

Executes the statement at the first label ("s1") if the arithmetic expression evaluates to a value less than 0; the statement at the second label ("s2") if the arithmetic expression evaluates to 0; or the statement at the third label ("s3") if the arithmetic expression evaluates to a value greater than 0.

IF (e) st

e Is a logical expression.

st Is a complete Fortran statement. The statement can be any statement except DO, END DO, END, block IF, or another logical IF statement.

IF (e) THEN block ELSE IF (e1) THEN block ELSE block END IF

e,e1 Are logical expressions.

block Is a series of zero or more Fortran statements (called a statement block).

NOTE: No additional statement can be placed after the IF THEN statement in a block IF construct. For example, the following statement is invalid in the block IF construct:

IF (e) THEN I = J

This statement is translated as the following logical IF statement:

IF (e) THENI = J