IF - Logical

Statement: Conditionally executes one statement based on the value of a logical expression. (This statement was called a logical IF statement in FORTRAN 77.)

IF (expr) stmt

expr

Is a scalar logical expression enclosed in parentheses.

stmt

Is any complete, unlabeled, executable Fortran statement, except for the following:

A CASE, DO, IF, FORALL, or WHERE construct
Another IF statement
The END statement for a program, function, or subroutine

When an IF statement is executed, the logical expression is evaluated first. If the value is true, the statement is executed. If the value is false, the statement is not executed and control transfers to the next statement in the program.

Example

The following examples show valid 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

The following shows another example:

   USE IFPORT
   INTEGER(4) istat, errget
   character(inchar)
   real x
   istat = getc(inchar)
   IF (istat) errget = -1
   ...
!   IF (x .GT. 2.3) call new_subr(x)
   ...

IF - Logical

Example

See Also