18-18 Programming
Example
1
A :
IF A==1
 THEN MSGBOX " A EQUALS 1" :
END:
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...
ELSE…
END...
Many conditions are automatically recognized by the HP 
39gs as error conditions and are automatically treated as 
errors in programs.
HP 39gs English.book  Page 18  Wednesday, December 7, 2005  11:24 PM