HP 39g+ - Manual (Page 224)

15-18 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
&
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/40G 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