Open Watcom FORTRAN 77 Language Reference

FORTRAN Statements
2.25 ELSE IF Statement
ELSE IF (e) THEN
where:
e
is a logical expression or integer arithmetic expression, in which case the result of the integer
expression is compared for inequality to the integer value 0.
The ELSE IF statement is used in conjunction with the IF statement. The range of the ELSE IF block
is terminated by another ELSE IF statement, an ELSE statement, or an END IF statement.
Example:
IF( A .LT. B )THEN
PRINT *, ’A is less than B’
ELSE IF( A .EQ. B )THEN
PRINT *, ’A is equal to B’
ELSE
PRINT *, ’A is greater than B’
END IF
Transfer of control into the range of an ELSE IF block is illegal. It is interesting to note that the ELSE
IF statement may be identified by a statement label but it must not be referenced by any statement!
Example:
* Illegal transfer into the range of
* an ELSE IF statement.
IF( A .EQ. 0.0 )GO TO 110
IF( A .LT. B )THEN
PRINT *, ’A is less than B’
ELSE IF( A .EQ. B )THEN
PRINT *, ’A is equal to B or’
110 PRINT *, ’A is equal to 0’
ELSE
PRINT *, ’A is greater than B’
END IF
The above is an example of an illegal attempt to branch into the range of an ELSE IF block.
For more information, see the chapter entitled "Program Structure Control Statements" on page 193.
ELSE IF Statement 55