## 5.7.2 Logical IF Statement

The logical IF statement conditionally executes a single Fortran statement based on the current value of a logical expression within the logical IF statement. It takes the following form:

    IF (e) st

e
  Is a logical expression.
st
  Is any complete, executable Fortran statement-except any of the block IF statements, DO, END DO, another logical IF statement, a SELECT CASE, CASE, or CASE DEFAULT statement.

The logical IF statement first evaluates the logical expression e and then acts as follows:

- If e is true, st executes.

- If e is false, control transfers to the next executable statement after the logical IF; st does not execute.

Examples

The following examples show valid logical IF statements:

    IF (J.GT.4 .OR. J.LT.1) GO TO 250

    IF (REF(J,K) .NE. HOLD) REF(J,K) = REF(J,K) * (-1.5D0)

    IF (ENDRUN) CALL EXIT

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