Open Watcom FORTRAN 77 Language Reference

Language Reference
Examples follow which illustrate the use of the two formats.
Example:
IF( I .EQ. 0 )THEN
PRINT *, ’I IS ZERO’
I = 1
END IF
If variable I is zero when the IF statement is executed, the string I IS ZERO will be printed, variable I
will be assigned the value 1, and the statement following the END IF will be executed. If variable I is not
zero when the IF statement is executed, control will pass to the statement following the END IF
statement.
Example:
IF( A .GT. B )THEN
PRINT *, ’A GREATER THAN B’
A = A - B
ELSE
PRINT *, ’A NOT GREATER THAN B’
END IF
If the value of variable A is greater than the value of variable B when this IF statement is executed, the
string A GREATER THAN B will be printed and variable A will be assigned the value of the expression A
- B. Control will then pass to the statement following the END IF statement.
If the value of variable A is not greater than the value of variable B when the IF statement is executed, the
string A NOT GREATER THAN B will be printed and control will pass to the statement following the
END IF statement.
9.3 ELSE IF
A further enhancement of the IF-THEN-ELSE construct is the ELSE IF statement which may be used in
the following two formats:
(a) IF( logical-expression-1 )THEN [: block-label]
statement(s)
ELSE IF( logical-expression-2 )THEN
statement(s)
...
END IF
(b) IF( logical-expression-1 )THEN [: block-label]
statement(s)
ELSE IF( logical-expression-2 )THEN
statement(s)
...
ELSE
statement(s)
END IF
194 ELSE IF