Open Watcom FORTRAN 77 Language Reference

Language Reference
Example:
* Illegal SELECT block - case value in more
* than one CASE block.
SELECT CASE ( I - 3 )
CASE (1,3,7:10)
statement(s)
CASE (5,6,8)
statement(s)
CASE (-3:-2+4)
statement(s)
END SELECT
The second CASE-block includes 8 which is already handled by the first CASE-block. As well, the third
CASE-block handles cases −3, −2, −1, 0, 1, 2 but the first CASE-block also handles case 1. Thus the
second and third CASE-ranges are in error.
When the SELECT statement case expression is evaluated as i, the case block whose range contains i is
executed and control passes to the statement following the END SELECT statement. If no range contains i,
control is transferred to the statement following the CASE DEFAULT statement, if one is specified. If the
CASE DEFAULT block is omitted and the case expression is out of range when the SELECT statement is
executed (that is, none of the CASE-blocks handles the particular expression value), control is passed to the
statement following the END SELECT statement and none of the CASE-blocks is executed.
Example:
SELECT CASE ( I )
CASE (1)
Y = Y + X
X = X * 3.2
CASE (2)
Z = Y**2 + X
PRINT *, X, Y, Z
CASE (3)
Y = Y * 13. + X
X = X - 0.213
CASE (4)
Z = X**2 + Y**2 - 3.0
Y = Y + 1.5
X = X * 32.0
PRINT *, ’CASE 4’, X, Y, Z
END SELECT
This example will execute in the manner described below for each of the possible values of variable I.
(i)
I is zero or negative:
- control will pass to the statement after the END SELECT statement
(ii) I = 1:
- the value of X will be added to Y
- X will be multiplied by 3.2
- control will pass to the statement after the END SELECT statement
(iii) I = 2:
- Z will be assigned the value of the expression Y**2 + X
- the values of X, Y and Z will be printed
- control will pass to the statement after the END SELECT statement
202 SELECT - END SELECT