Getting Started with the Program Editor. Texas Instruments TI-Nspire CX
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Getting Started with the Program Editor
You can create user-defined functions or programs by typing definition statements on the Calculator entry line or by using the Program Editor. The
Program Editor offers some advantages, and it is covered in this section. For more information, see Calculator.
• The editor has programming templates and dialog boxes to help you define functions and programs using correct syntax.
• The editor lets you enter multiple-line programming statements without requiring a special key sequence to add each line.
• You can easily create private and public library objects (variables, functions, and programs). For more information, see Libraries.
Launching the Program Editor
▶
To add a new Program Editor page in the current problem:
From the toolbar, click
Insert > Program Editor > New
.
Handheld: Press
~ and select Insert > Program Editor > New .
Note:
The editor is also accessible from the Functions & Programs menu of a Calculator page.
À
Program Editor menu – This menu is available anytime you are in the
Program Editor work area using the Normal view mode.
Á
Program Editor work area
Getting Started with the Program Editor 563
Â
Status line shows line-number information and the name of the function or program being edited. An asterisk (
*
) indicates that this function is “dirty,” which means that it has changed since the last time its syntax has been checked and it has been stored.
Defining a Program or Function
Starting a new Program Editor
1.
Make sure you are in the document and problem in which you want to create the program or function.
2.
Click Insert button on the application toolbar, and select Program Editor
> New . (On the handheld, press
~ and select Insert > Program Editor >
New .)
3.
Type a name for the function or program you are defining.
4.
Select the
Type
(
Program or
Function
).
5.
Set the
Library Access
:
To use the function or program only from the current document and problem, select None .
To make the function or program accessible from any document but not visible in the Catalog, select LibPriv .
To make the function or program accessible from any document and also visible in the Catalog, select
LibPub (Show in Catalog)
. For more information, see Libraries.
6.
Click OK .
A new instance of the Program Editor opens, with a template matching the selections you made.
564 Getting Started with the Program Editor
Entering Lines into a Function or Program
The Program Editor does not execute the commands or evaluate expressions as you type them. They are executed only when you evaluate the function or run the program.
1.
If your function or program will require the user to supply arguments, type parameter names in the parentheses that follow the name. Separate parameters with a comma.
2.
Between the Func and EndFunc (or Prgm and EndPrgm) lines, type the lines of statements that make up your function or program.
You can either type the names of functions and commands or insert them from the Catalog.
A line can be longer than the width of the screen; if so, you might have to scroll to view the entire statement.
After typing each line, press
Enter
. This inserts a new blank line and lets you continue entering another line.
Use the ◄, ►, ▲, and ▼ arrow keys to scroll through the function or program for entering or editing commands.
Getting Started with the Program Editor 565
Inserting Comments
A comment symbol (©) lets you enter a remark. Comments can be useful to someone viewing or editing the program. Comments are not displayed when the program runs, and they have no effect on program flow.
Define LibPub volcyl(ht,r) =
Prgm
©volcyl(ht,r) => volume of cylinder
Disp “Volume =”, approx(p ¦ r
2
¦ ht)
À
©This is another comment.
EndPrgm
À
Comment showing required syntax. Because this library object is public and this comment is the first line in a Func or Prgm block, the comment is displayed in the Catalog as help. For more information, see Libraries.
To insert a comment:
1.
Position the cursor at the end of the line in which you want to insert a comment.
2.
From the
Actions menu, click
Insert Comment
.
3.
Type the text of the comment after the © symbol.
Checking Syntax
The Program Editor lets you check the function or program for correct syntax.
▶
From the Check Syntax & Store menu, click Check Syntax .
If the syntax checker finds any syntax errors, it displays an error message and tries to position the cursor near the first error so you can correct it.
566 Getting Started with the Program Editor
Storing the Function or Program
You must store your function or program to make it accessible. The Program
Editor automatically checks the syntax before storing.
An asterisk (*) is displayed in the upper left corner of the Program Editor to indicate that the function or program has not been stored.
▶
From the Check Syntax & Store menu, click Check Syntax & Store .
If the syntax checker finds any syntax errors, it displays an error message and tries to position the cursor near the first error.
If no syntax errors are found, the message “Stored successfully“is displayed in the status line at the top of the Program Editor.
Note:
If the function or program is defined as a library object, you must also save the document in the designated library folder and refresh libraries to make the object accessible to other documents. For more information, see
Libraries.
Viewing a Program or Function
1.
From the
Actions menu, click
View
.
2.
If the function or program is a library object, select its library from the
Location list.
3.
Select the function or program name from the Name list.
The function or program is displayed in a viewer.
Getting Started with the Program Editor 567
4.
Use the arrow keys to view the function or program.
5.
If you want to edit the program, click Edit .
Handheld: Press e to highlight
Edit
, and then press
·
.
Note:
The
Edit selection is available only for functions and programs defined in the current problem. To edit a library object, you must first open its library document.
Opening a Function or Program for Editing
You can open a function or program from the current problem only.
Note:
You cannot modify a locked program or function. To unlock the object, go to a Calculator page and use the unLock command.
1.
Display the list of available functions and programs.
From the Actions menu, click Open .
2.
Click the item to open.
Importing a Program from a Library
You can import a function or program defined as a library object into a Program
Editor within the current problem. The imported copy is not locked, even if the original is locked.
1.
From the
Actions menu, click
Import
.
568 Getting Started with the Program Editor
2.
Select the
Library Name
.
3.
Select the Name of the object.
4.
If you want the imported object to have a different name, type the name under Import As .
Creating a Copy of a Function or Program
When creating a new function or program, you might find it easier to start with a copy of the current one. The copy that you create is not locked, even if the original is locked.
1.
From the
Actions menu, click
Create Copy
.
2.
Type a new name, or click
OK to accept the proposed name.
3.
If you want to change the access level, select Library Access , and select a new level.
Renaming a Program or Function
You can rename and (optionally) change the access level of the current function or program.
1.
From the Actions menu, click Rename .
Getting Started with the Program Editor 569
2.
Type a new name, or click OK to accept the proposed name.
3.
If you want to change the access level, select
Library Access
, and select a new level.
Changing the Library Access Level
1.
From the
Actions menu, click
Change Library Access
.
2.
Select the
Library Access
:
To use the function or program only from the current Calculator problem, select
None
.
To make function or program accessible from any document but not visible in the Catalog, select LibPriv .
To make the function or program accessible from any document and also visible in the Catalog, select
LibPub
.
Finding Text
1.
From the
Actions menu, click
Find
.
2.
Type the text that you want to find, and click OK .
If the text is found, it is highlighted in the program.
If the text is not found, a notification message is displayed.
Finding and Replacing Text
1.
From the Actions menu, click Find and Replace .
570 Getting Started with the Program Editor
2.
Type the text that you want to find.
3.
Type the replacement text.
4.
Click
Replace to replace the first occurrence after the cursor position.
—or—
Click Replace All to replace every occurrence.
Note:
If the text is found in a math template, a message is displayed to warn you that your replacement text will replace the whole template—not just the found text.
Closing the Current Function or Program
▶
From the Actions menu, click Close .
If the function or program has unstored changes, you are prompted to check syntax and store before closing.
Running Programs and Evaluating Functions
After defining and storing a function or program, you can use it from an application. All the applications can evaluate functions, but only the Calculator and Notes applications can run programs.
The program statements are executed in sequential order (although some commands alter the program flow). The output, if any, is displayed in the application’s work area.
• Program execution continues until it reaches the last statement or a
Stop command.
• Function execution continues until it reaches a
Return command.
• To stop a program or function manually,
Windows®: Hold down the F12 key and press Enter repeatedly.
Getting Started with the Program Editor 571
Mac®: Hold down the F5 key and press Enter repeatedly.
Handheld: Hold down the c key and press
· repeatedly.
Using Short and Long Names
Anytime you are in the same problem where an object is defined, you can access it by entering its short name (the name given in the object’s
Define command). This is the case for all defined objects, including private, public, and non-library objects.
You can access a library object from any document by typing the object’s long name. A long name consists of the name of the object’s library document followed by a backslash “\” followed by the name of the object. For example, the long name of the object defined as func1 in the library document lib1 is lib1\func1 . To type the “\” character on the handheld, press g p
.
Note:
If you cannot remember the exact name or the order of arguments required for a private library object, you can open the library document or use the Program Editor to view the object. You also can use getVarInfo to view a list of objects in a library.
Using a Public Library Function or Program
1.
Make sure you have defined the object in the document’s first problem, stored the object, saved the library document in the MyLib folder, and refreshed the libraries.
2.
Open the TI-Nspire™ application in which you want to use the function or program.
Note:
All applications can evaluate functions, but only the Calculator and
Notes applications can run programs.
3.
Open the Catalog and use the library tab to find and insert the object.
—or—
Type the name of the object. In the case of a function or program, always follow the name with parentheses.
libs2\func1()
4.
If the program requires you to supply one or more arguments, type the values or variable names inside the parentheses.
libs2\func1(34,power)
572 Getting Started with the Program Editor
5.
Press
·
.
Using a Private Library Function or Program
To use a Private library object, you must know its long name. For example, the long name of the object defined as func1 in the library document lib1 is lib1\func1
.
Note:
If you cannot remember the exact name or the order of arguments required for a private library object, you can open the library document or use the Program Editor to view the object.
1.
Make sure you have defined the object in the document’s first problem, stored the object, saved the library document in the MyLib folder, and refreshed the libraries.
2.
Open the TI-Nspire™ application in which you want to use the function or program.
Note:
All applications can evaluate functions, but only the Calculator and
Notes applications can run programs.
3.
Type the name of the object. In the case of a function or program, always follow the name with parentheses.
libs2\func1()
4.
If the object requires you to supply one or more arguments, type the values or variable names inside the parentheses.
libs2\func1(34,power)
5.
Press
·
.
Running a Non-Library Program or Function
1.
Make sure you are in the same problem in which the function or program is defined.
2.
Type the name of the function or program on the entry line.
—or—
Press h to select the name from a list.
You must always include a set of parentheses after the name.
prog1()
Getting Started with the Program Editor 573
If the function or program requires you to supply one or more arguments, type the values or variable names inside the parentheses.
prog1(34,power)
3.
Press
·
.
Interrupting a Running Program
While a function or program is running, the busy pointer
} is displayed.
▶
To stop the function or program,
Windows®: Hold down the
F12 key and press
Enter repeatedly.
Mac®: Hold down the F5 key and press Enter repeatedly.
Handheld: Hold down the c key and press
· repeatedly.
A message is displayed. To edit the function or program in the Program
Editor, select
Go To
. The cursor appears at the command where the break occurred.
Getting Values into a Program
You can choose from several methods to supply the values that a function or program uses in calculations.
Embedding the Values Within the Program or Function
This method is useful primarily for values that must be the same each time the program or function is used.
1.
Define the program.
Define calculatearea()=
Prgm w:=3 h:=23.64
area:=w*h
EndPrgm
2.
Run the program.
calculatearea()
:area 70.92
574 Getting Started with the Program Editor
Letting the User Assign the Values to Variables
A program or function can refer to variables created beforehand. This method requires users to remember the variable names and to assign values to them before using the object.
1.
Define the program.
Define calculatearea()=
Prgm area:=w*h
EndPrgm
2.
Supply the variables, and then run the program.
w:=3 : h:=23.64
calculatearea()
:area 70.92
Letting the User Supply the Values as Arguments
This method lets users pass one or more values as arguments within the expression that calls the program or function.
The following program, volcyl , calculates the volume of a cylinder. It requires the user to supply two values: height and radius of the cylinder.
1.
Define the volcyl program.
Definevolcyl(height,radius) =
Prgm
Disp "Volume =", approx(p ¦ radius
2 height)
EndPrgm
¦
2.
Run the program to display the volume of a cylinder with a height of 34 mm and a radius of 5 mm.
volcyl(34,5) Volume = 534.071
Note:
You do not have to use the parameter names when you run the volcyl program, but you must supply two arguments (as values, variables, or expressions). The first must represent the height, and the second must represent the radius.
Getting Started with the Program Editor 575
Requesting the Values from the User (Programs Only)
You can use the Request and RequestStr commands in a program to make the program pause and display a dialog box prompting the user for information.
This method does not require users to remember variable names or the order in which they are needed.
You cannot use the Request or RequestStr command in a function.
1.
Define the program.
Define calculatearea()=
Prgm
Request "Width: ",w
Request "Height: ",h area:=w*h
EndPrgm
2.
Run the program and respond to the requests.
calculatearea() : area
Width: 3 (3 entered as a response)
Height: 23.64 (23.64 entered as a response)
70.92
Use RequestStr instead of Request when you want the program to interpret the user’s response as a character string rather than a math expression. This avoids requiring the user to enclose the response in quotation marks (““).
Displaying Information from a Function or Program
A running function or program does not display intermediate calculated results unless you include a command to display them. This is an important difference between performing a calculation on the entry line and performing it in a function or program.
The following calculations, for example, do not display a result in a function or program (although they do from the entry line).
© x:=12•6
576 Getting Started with the Program Editor
cos(π/4)
©
Displaying Information in the History
You can use the
Disp command in a program or function to display information, including intermediate results, in the history.
©
Disp 12•6
Disp "Result:",cos(π/4)
©
Displaying Information in a Dialog Box
You can use the
Text command to pause a running program and display information in a dialog box. The user clicks
OK to continue or clicks
Cancel to stop the program.
You cannot use the
Text command in a function.
©
Text "Area=" & area
©
Note:
Displaying a result with
Disp or
Text does not store that result. If you expect to refer later to a result, store it to a global variable.
© cos(π/4)→maximum
Disp maximum
©
Using Local Variables
A local variable is a temporary variable that exists only while a user-defined function is being evaluated or a user-defined program is running.
Example of a Local Variable
The following program segment shows a For...EndFor
loop (which is discussed later in this module). The variable
i
is the loop counter. In most cases, the variable
i
is used only while the program is running.
Getting Started with the Program Editor 577
Local i
À
For i,0,5,1
Disp i
EndFor
Disp i
À
Declares variable
i
as local.
Note:
When possible, declare as local any variable that is used only within the program and does not need to be available after the program stops.
What Causes an Undefined Variable Error Message?
An Undefined variable error message is displayed when you evaluate a userdefined function or run a user-defined program that references a local variable that is not initialized (assigned a value).
For example:
Define fact(n)=Func
Local m
À
While n>1
n¦m&m: n–1&n
EndWhile
Return m
EndFunc
À
Local variable
m
is not assigned an initial value.
Initialize Local Variables
All local variables must be assigned an initial value before they are referenced.
Define fact(n)=Func
Local m: 1&m
À
While n>1
n¦m&m: n–1&n
EndWhile
Return m
EndFunc
À
1 is stored as the initial value for
m
.
578 Getting Started with the Program Editor
Note (CAS):
Functions and programs cannot use a local variable to perform symbolic calculations.
CAS: Performing Symbolic Calculations
If you want a function or program to perform symbolic calculations, you must use a global variable instead of a local. However, you must be certain that the global variable does not already exist outside of the program. The following methods can help.
• Refer to a global variable name, typically with two or more characters, that is not likely to exist outside of the function or program.
• Include DelVar within a program to delete the global variable, if it exists, before referring to it. ( DelVar does not delete locked or linked variables.)
Differences Between Functions and Programs
A function defined in the Program Editor is similar to the functions built into the
TI-Nspire™ Software.
• Functions must return a result, which can be graphed or entered in a table.
Programs do not return a result.
• You can use a function (but not a program) within an expression. For example: 3 ¦ func1(3) is valid, but not 3 ¦ prog1(3) .
• You can run programs from Calculator and Notes applications only.
However, you can evaluate functions in Calculator, Notes, Lists &
Spreadsheet, Graphs & Geometry, and Data & Statistics.
• A function can refer to any variable; however, it can store a value to a local variable only. Programs can store to local and global variables.
Note:
Arguments used to pass values to a function are treated as local variables automatically. If you want to store to any other variables, you must declare them as Local from within the function.
• A function cannot call a program as a subroutine, but it can call another user-defined function.
• You cannot define a program within a function.
• A function cannot define a global function, but it can define a local function.
Getting Started with the Program Editor 579
Calling One Program from Another
One program can call another program as a subroutine. The subroutine can be external (a separate program) or internal (included in the main program).
Subroutines are useful when a program needs to repeat the same group of commands at several different places.
Calling a Separate Program
To call a separate program, use the same syntax that you use to run the program from the entry line.
Defining and Calling an Internal Subroutine
To define an internal subroutine, use the
Define command with
Prgm...EndPrgm
. Because a subroutine must be defined before it can be called, it is a good practice to define subroutines at the beginning of the main program.
An internal subroutine is called and executed in the same way as a separate program.
Define subtest1()=
Prgm
local subtest2
À
Define subtest2(x,y)=
Á
Prgm
Disp x,y
EndPrgm
©Beginning of main program
For i,1,4,1
subtest2(i,I*1000)
EndFor
EndPrgm
Â
580 Getting Started with the Program Editor
À
Declares the subroutine as a local variable.
Á
Defines the subroutine.
Â
Calls the subroutine.
Note:
Use the Program Editor’s
Var menu to enter the
Define and
Prgm...EndPrgm
commands.
Notes about Using Subroutines
At the end of a subroutine, execution returns to the calling program. To exit a subroutine at any other time, use
Return with no argument.
A subroutine cannot access local variables declared in the calling program.
Likewise, the calling program cannot access local variables declared in a subroutine.
Lbl commands are local to the programs in which they are located. Therefore, a
Goto command in the calling program cannot branch to a label in a subroutine or vice versa.
Avoiding Circular-Definition Errors
When evaluating a user-defined function or running a program, you can specify an argument that includes the same variable that was used to define the function or create the program. However, to avoid circular-definition errors, you must assign a value for variables that are used in evaluating the function or running the program. For example: x+1&x
À
– or –
For i,i,10,1
Disp i
À
EndFor
À
Causes a Circular definition error message if x or i does not have a value.
The error does not occur if x or i has already been assigned a value.
Controlling the Flow of a Function or Program
When you run a program or evaluate a function, the program lines are executed in sequential order. However, some commands alter the program flow. For example:
Getting Started with the Program Editor 581
• Control structures such as
If...EndIf
commands use a conditional test to decide which part of a program to execute.
• Loop commands such as For...EndFor
repeat a group of commands.
Using If, Lbl, and Goto to Control Program Flow
The
If command and several
If...EndIf
structures let you execute a statement or block of statements conditionally, that is, based on the result of a test (such as x>5).
Lbl
(label) and
Goto commands let you branch, or jump, from one place to another in a function or program.
The
If command and several
If...EndIf
structures reside on the Program Editor’s
Control menu.
When you insert a structure such as
If...Then...EndIf
, a template is inserted at the cursor location. The cursor is positioned so that you can enter a conditional test.
If Command
To execute a single command when a conditional test is true, use the general form:
If x>5
Disp "x is greater than 5"
À
Disp x
Á
À
Executed only if x>5; otherwise, skipped.
Á
Always displays the value of x.
In this example, you must store a value to x before executing the
If
command.
If...Then...EndIf Structures
To execute one group of commands if a conditional test is true, use the structure:
If x>5 Then
Disp "x is greater than 5"
À
2¦x&x
À
EndIf
Disp x
Á
À
Executed only if x>5.
582 Getting Started with the Program Editor
Á
Displays the value of:
2x if x>5
x if x{5
Note: EndIf marks the end of the Then block that is executed if the condition is true.
If...Then...Else...EndIf Structures
To execute one group of commands if a conditional test is true and a different group if the condition is false, use this structure:
If x>5 Then
Disp "x is greater than 5"
À
2¦x&x
À
Else
Disp "x is less than or equal to 5"
Á
5¦x&x
Á
EndIf
Disp x
Â
À
Executed only if x>5.
Á
Executed only if x{5.
Â
Displays value of:
2x if x>5
5x if x{5
If...Then...ElseIf... EndIf Structures
A more complex form of the
If command lets you test for multiple conditions.
Suppose you want a program to test a user-supplied argument that signifies one of four options.
To test for each option (If Choice=1, If Choice=2, and so on), use the
If...Then...ElseIf...EndIf
structure.
Lbl and Goto Commands
You can also control the flow by using
Lbl
(label) and
Goto commands. These commands reside on the Program Editor’s
Transfers menu.
Use the Lbl command to label (assign a name to) a particular location in the function or program.
Getting Started with the Program Editor 583
Lbl
labelName
name to assign to this location (use the same naming convention as a variable name)
You can then use the Goto command at any point in the function or program to branch to the location that corresponds to the specified label.
Goto
labelName
specifies which Lbl command to branch to
Because a
Goto command is unconditional (it always branches to the specified label), it is often used with an
If command so that you can specify a conditional test. For example:
If x>5
Goto GT5
À
Disp x
--------
--------
Lbl GT5
Á
Disp "The number was > 5"
À
If x>5, branches directly to label GT5.
Á
For this example, the program must include commands (such as Stop ) that prevent
Lbl
GT5 from being executed if x{5.
Using Loops to Repeat a Group of Commands
To repeat the same group of commands successively, use one of the loop structures. Several types of loops are available. Each type gives you a different way to exit the loop, based on a conditional test.
Loop and loop-related commands reside on the Program Editor’s Control and
Transfers menus.
When you insert one of the loop structures, its template is inserted at the cursor location. You can then begin entering the commands that will be executed within the loop.
For...EndFor Loops
A
For...EndFor
loop uses a counter to control the number of times the loop is repeated. The syntax of the
For command is:
584 Getting Started with the Program Editor
For
variable
,
À
begin
,
Á
end
,
Â
increment
Ã
À
Name of a variable to be used as a counter
Á
Value assigned to
variable
when the For loop begins.
Â
Value compared to the current value of
variable
at each iteration of the loop. The loop exits when
variable
exceeds
end
.
Ã
Value added to
variable
at each iteration of the loop (This argument is optional. The default
increment
is 1.)
At each iteration of the For loop, the
variable
value is compared to the
end
value. If
variable
does not exceed
end
, the commands within the For...EndFor
loop are executed and the loop repeats; otherwise, control jumps to the command following
EndFor
.
Note:
The
For command automatically increments the counter variable so that the function or program can exit the loop after a certain number of repetitions.
At the end of the loop (
EndFor
), control loops back to the
For command, where the counter variable is incremented and compared to
end
.
For example:
For i,0,5,1
Disp i
À
EndFor
Disp i
Á
À
Displays 0, 1, 2, 3, 4, and 5.
Á
Displays 6. When
variable
increments to 6, the loop is not executed.
Notes:
• You can declare
variable
as local if it does not need to be saved after the function or program stops.
Getting Started with the Program Editor 585
• You can set
end
to a value less than
begin
, provided you also set
increment
to a negative value.
While...EndWhile Loops
A
While...EndWhile
loop repeats a block of commands as long as a specified condition is true. The syntax of the
While command is:
While
condition
When
While is executed,
condition
is evaluated. If
condition
is true, the loop is executed; otherwise, control jumps to the command following EndWhile .
Note:
The
While command does not automatically change the condition. You must include commands that allow the function or program to exit the loop.
At the end of the loop (
EndWhile
), control jumps back to the
While command, where condition is re-evaluated.
To execute the loop the first time, the condition must initially be true.
• Any variables referenced in the condition must be set before the
While command. (You can build the values into the function or program, or you can prompt the user to enter the values.)
• The loop must contain commands that change the values in the condition, eventually causing it to be false. Otherwise, the condition is always true and the function or program cannot exit the loop (called an infinite loop).
For example:
0&x
À
While x<5
Disp x
Á
x+1&x
Â
EndWhile
Disp x
Ã
À
Initially sets x.
586 Getting Started with the Program Editor
Á
Displays 0, 1, 2, 3, and 4.
Â
Increments x.
Ã
Displays 5. When x increments to 5, the loop is not executed.
Loop...EndLoop Loops
A
Loop...EndLoop
creates an infinite loop, which is repeated endlessly. The
Loop command does not have any arguments.
Typically, you insert commands in the loop that let the program exit from the loop. Commonly used commands are:
If
,
Exit
,
Goto
, and
Lbl
(label). For example:
0&x
Loop
Disp x
x+1&x
If x>5
À
Exit
EndLoop
Disp x
Á
À
An If command checks the condition.
Á
Exits the loop and jumps to here when
x
increments to 6.
Note:
The Exit command exits from the current loop.
In this example, the If command can be anywhere in the loop.
When the If command is:
The loop is:
At the beginning of the loop
Executed only if the condition is true.
At the end of the loop Executed at least once and repeated only if the condition is true.
Getting Started with the Program Editor 587
The
If command could also use a
Goto command to transfer program control to a specified
Lbl
(label) command.
Repeating a Loop Immediately
The
Cycle command immediately transfers program control to the next iteration of a loop (before the current iteration is complete). This command works with
For...EndFor
,
While...EndWhile
, and
Loop...EndLoop
.
Lbl and Goto Loops
Although the
Lbl
(label) and
Goto commands are not strictly loop commands, they can be used to create an infinite loop. For example:
As with
Loop...EndLoop
, the loop should contain commands that let the function or program exit from the loop.
Changing Mode Settings
Functions and programs can use the setMode() function to temporarily set specific calculation or result modes. The Program Editor’s Mode menu makes it easy to enter the correct syntax without requiring you to memorize numeric codes.
Note:
Mode changes made within a function or program definition do not persist outside the function or program.
Setting a Mode
1.
Position the cursor where you want to insert the setMode function.
2.
From the
Mode menu, click the mode to change, and click the new setting.
The correct syntax is inserted at the cursor location. For example: setMode(1,3)
588 Getting Started with the Program Editor
Debugging Programs and Handling Errors
After you write a function or program, you can use several techniques to find and correct errors. You can also build an error-handling command into the function or program itself.
If your function or program allows the user to select from several options, be sure to run it and test each option.
Techniques for Debugging
Run-time error messages can locate syntax errors but not errors in program logic. The following techniques may be useful.
• Temporarily insert Disp commands to display the values of critical variables.
• To confirm that a loop is executed the correct number of times, use
Disp to display the counter variable or the values in the conditional test.
• To confirm that a subroutine is executed, use
Disp to display messages such as “Entering subroutine” and “Exiting subroutine” at the beginning and end of the subroutine.
• To stop a program or function manually,
Windows®: Hold down the F12 key and press Enter repeatedly.
Mac®: Hold down the
F5 key and press
Enter repeatedly.
Handheld: Hold down the c key and press
· repeatedly.
Error-handling Commands
Command Description
Try...EndTry
Defines a block that lets a function or program execute a command and, if necessary, recover from an error generated by that command.
ClrErr
PassErr
Clears the error status and sets system variable errCode to zero. For an example of using errCode, see the Try command in the Reference Guide.
Passes an error to the next level of the
Try...EndTry
block.
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590
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