HP 39g+ - Manual (Page 228)

16-18 Programming
IF... THEN... ELSE...
END Executes the true-clause sequence of commands if the test-
clause is true, or the false-clause sequence of commands
if the test-clause is false.
IF test-clause
THEN true-clause ELSE false-clause END
Example
1 X A
:
IF A==1
THEN MSGBOX "A EQUALS 1"
:
ELSE MSGBOX "A IS NOT EQUAL TO 1"
:
END
CASE...END Executes a series of test-clause commands that execute
the appropriate true-clause sequence of commands. Its
syntax is:
CASE
IF
test-clause
1
THEN true-clause
1 END
IF test-clause
2 THEN true-clause
2 END
.
.
.
IF
test-clause
n THEN true-clause
n END
END
When CASE is executed, test-clause
1
is evaluated. If the
test is true, true-clause
1
is executed, and execution skips
to END. If test-clause
1
if false, execution proceeds to test-
clause
2
. Execution with the CASE structure continues until
a true-clause is executed (or until all the test-clauses
evaluate to false).
IFERR...
THEN...
END... Many conditions are automatically recognized by the hp
39g+ as error conditions and are automatically treated
as errors in programs.
IFERR...THEN...END allows a program to intercept error
conditions that otherwise would cause the program to
abort. Its syntax is:
IFERR trap-clause
THEN error-clause END