7120983 16 debugging techniques

8/14/2019 7120983 16 Debugging Techniques

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Debugging


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Debugging

Program ... . Breakpoint ... .

ABAP/4 Editor

ABAP/4

Debugger

Debugging

Program B170D051

Breakpoints

Object List

Development object ... ... ...

. . .

Test/execute

. . .

Any screen

... ... ... System Help

. . .

Utilities

. . .. . .

Debug ABAP/4

. . ./h

Branching to Debugging Mode


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Debugging Mode

PROGRAM B170D051.

DATA: DIFF TYPE P,...

COMPUTE DATE_1 = SY-DATUM.

..

.

Execute Single step Execute Continue Table

DATE_1 00000000

SY-DATUM 19940223

Variables

X R

R

R

R

R

O S V F T P

View pushbuttons

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The Most Important Debugging Functions

Single Step Processes the next program line.

Execute In contrast to the single step, executes

all processing steps belonging to one line.

Continue

Table

Processing continues until the next breakpoint oruntil the end of the program.

Displays the contents of internal tables.

Breakpoint With the functions of this menu you

define breakpoints.Editor You go to the ABAP/4 editor.

Hexadecimal-

display

Data contents can be displayed in hexedecimal format.

Debugging


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Setting Breakpoints

Menu

Keyword

Utilities-> Breakpoints

BREAK-POINT

Line selection (double-click)

Menu: Breakpoint

-> Set/delete

Goto

-> Breakpoints

ABAP/4 Editor

Debugging mode

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Debugging


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Other Debugger Features

Replace Field ContentsReplace Field Contents

Display/Change Internal Table EntriesDisplay/Change Internal Table Entries

Display Output ListDisplay Output List

Switch to ABAP/4 EditorSwitch to ABAP/4 Editor

Database ReleaseDatabase Release

Activate/Deactivate BreakpointsActivate/Deactivate Breakpoints

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A detailed explanation of ABAP/4 Debugging.

The slides for the ABAP/4 Development Workbenchs on lineDebuggers Contain the following topics,

Online debugging tools.Starting the debuggerThe debuggers six viewsUsing break pointsSetting static break pointsSetting dynamic break pointsSetting watch pointsSetting breakpoints at keywords or eventsDeleting and deactivating breakpointsStepping through program codes

Displaying field contents

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Displaying Internal tablesDisplaying ABAP/4 listsReplacing field values at runtimeChanging internal tables at runtimeSwitching to the ABAP/4 EditorReleasing the database during debugging

Online debugging tools : A review

The ABAP/4 Debugger lets you stop a program during runtime and

examine the flow and results of each statement during

execution.Stepping through a program with the debugger helps you to

detect and correct errors in your code.This documentation is designed for

developers new to the Workbenchs debugging facilities or for those whowant to learn the tool to use the tool more effectively.

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After working through this slides , you should be able to debugg both

familiar and unfamiliar programs effectively. With this slides, you will

learn how to

Switch on the debugger

Set and delete static and dynamic break points.

Set watch points

Stop a program at specific key words or events or when a field contentschange.

Continue processing after an interrupt.

Display field contents during runtime.

Display the contents of an internal table.

Change field contents for testing purposes.Change the contents of an internal table.

Display and use debuggers six different views.

Debugging


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Debugging Strategies form within ABAP/4 Development Work bench. We

can set breakpoints in a program and then start the program within the

Debugger.Alternatively, we can run the program in the debugger without

any breakpoints.

A Breakpoint is a signal within a line of code that tells the ABAP/4runtime processor to interrupt the program at the line.Setting break

points is a good strategy if we want to examine a program:

After the system has already processed certain events

Just before a specific event is carried out

By skipping quickly to a specific routines or calls

Debugging


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Starting the Debugger

On running a program in the debugging mode the following steps can be

followed.

In the object browser ,

Select a report or transaction.

Choose debugging in the ABAP/4 editor initial screen

Choose ProgramExecuteDebugging or choose debugging.From any screen , Choose SystemUtilitiesDebug ABAP/4.Debuggers six views

A debugger selects between six different views , by selecting appropriateview name in debuggers menu.

Or by pressing small push-buttons at right corner of each debugging

screen.

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These buttons has following specific meaning.

O Overview - Displays the structure of the program to be

debugged.S Call stack Displays an active event chain and the call

sequence up to the current breakpoint.V Variables Displays the contents up to four fields or field

strings.F Field display Displays the fields content and technical

characteristics.T Table Display Displays the content of an internal table.P Programs Displays all programs needed to run the report

or transaction to be debugged, including

system program

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Structure of the Debugging view.

Each debugging view has the same structure. The top half of the screen

displays a portion of the programs source code. The lower half shows

information specific to that particular view .Next to the Line Display

appears two push buttons + sign and sign , to scroll through the

program code.

The line currently ready for processing is indicated by >.A small stopsign appears to the left of each dynamic break point .A red light appears

at the bottom of screen after reaching a break point.

If no breakpoints are present, the light is green.

Using Breakpoints

A breakpoint is a signal within a programs code , which tells the ABAP/4

processor to interrupt the program at a particular point. The type of

breakpoint depends on the purpose of debugging.

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Following are the types of breakpoints.

Static

These are user independent , set directly into a programs code with the

editor. User dependent breakpoints also is possible.

Dynamic

Set within the ABAP/4 debugger or editor. This type is invisible when theprogram is displayed in the editor.

Watch points

Set within the ABAP/4 debugger .Watch points are field-specific. This is

used to observe changes to a particular field .The debugger interruptsthe program when fields content change. Only one watch point is

possible at a time.

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Key word or event breakpoints

Set within the ABAP/4 debugger. The debugger interrupts the program

when the ABAP/4 processor comes in contact with a specific key word or

event in programs code.

When a static breakpoint is used?

Static break point are generally user-independent. On setting this

breakpoint , every use who executes the program encounters the

breakpoint. This is used when several developers are working in thesame program, and all wants to the program to interrupt at the same

place during execution.

These breakpoints are visible in the programs code.

When a dynamic breakpoint is used?Dynamic break point is user-specific. If we want to interrupt a

program when we execute and while others are running, we use dynamic

break-point.

Dynamic breakpoints are more flexible than static breakpoint , they

can be removed or deactivated during runtime.

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When to use watch points.

We can set watchpoints only from within the debugger.They are useful ifwe want to interrupt a program only when there is a change in a particular

field or a field string. We can set and remove watch points as

Needed .This , as dynamic breakpoint , does not disturb the other users

of the same program.

When to use breakpoints at Keywords or Events.

From within debugger , we can allocate breakpoint for specific ABAP/4

keywords or program events.

This is useful if we do not know exactly where a key word or event occurs

, but still want the program to be interrupted just before the command orevent is carried out.

Setting Static Breakpoints.

To set a static break point use BREAK-POINT keyword.

Place the break point on the line where to interrupt the program:

Debugging


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REPORT RSDEBUG1

CHECK ACCOUNT

IF SY-SUBRC NE 0.

BREAK-POINT.

ENDIF.

.

When we start the report , ABAP/4 interrupts the processing at the breakpoint.

We can number breakpoints like BREAK-POINT1 ,BREAK-POINT2..for

easier identification.

Removing Breakpoints.It is necessary to remove the breakpoints after debugging .Use function

Utilities Global search to help in locating break-points in largerprograms. It is necessary to remove breakpoints since it may cause

serious disruptions in productive process.

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Setting Dynamic Breakpoints

We can set dynamic breakpoint , without changing the programs code.

Following are the steps to set a breakpoint in ABAP/4 Editor.

Place the cursor on the line where to position the breakpoint.

Choose Utilities BreakpointSet.A display of all breakpoints in a program can be obtained by selecting

UtilitiesBreakpointsDisplay function.

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Setting Watchpoints.

A watch point is set to interrupt a program when the contents of a

specific field or a string change.

Following are the steps to set a watch point.

Locate the field in the code.

Place the cursor directly on the field.Choose F for Field display. The debugger displays the field

display view.The field view displays the fields content and offers detailed

information about its technical nature.Set the watch point checkbox to the right of fields name.Continue executing the program by choosing Continue.

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Displaying the current watchpoint.

Choose Goto Breakpoints .The system displays the breakpointoverview screen.

Setting Breakpoints at keywords or Events.

If we want to interrupt the program directly before a certain keyword,

event or a subroutine , we use this facility.We can achieve this with the following steps.

Choose either BreakpointBreakpoint atAt event/FORM orBreakpointBreakpoint atAt key word.

The system will display a small screen prompting to enter name

event or keyword.

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The system will set a breakpoint each time the key word , event

for subroutine appears in the program.For break point in form routines , it is possible to access the

current program , not external subroutine calls.Choose OK.

To interrupt a program whenever the system return is not equal

to

zero, select Breakpoint Breakpoint atAt SY-SUBRC0.

Debugging


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Deleting and Deactivating Breakpoints.

During the debugging process, the breakpoints in the earlier run need to

be ignored.In case of static dynamic breakpoints it is flexible during

runtime. In case of dynamic breakpoints, there are more possibilities of

controlling it ,than static breakpoints.

Deactivating Static Breakpoints.

Sataic breakpoints are hard coded directly into program using BREAK-POINT or BREAK. This is deactivated by deleting the BREAK-POINT or

BREAK keywords.

Breakpoints and breakpoints at keywords and events.

Dynamic breakpoint are not written directly in the programs code. It can

be deleted or temporarily deactivated and reactivate breakpoints at

keywords or events as the same way as dynamic breakpoints.

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Stepping through program code.

From within the debugger several options for stepping through the

program.

Single step : Execute a program statement by statement. If single step is

chosen while on a line that calls a FORM routine , for example the next

mouse click carries to the called routine.After stepping the way through

the subroutine, returns to the line of code directly following thesubroutine call.

Execute : Process a program line by line. On choosing Execute while on

a line, that calls a FORM routine, the debugger executes the subroutine

subroutine and halts at the line of code directly following the call.Thus this skips over the lines of the subroutine itself.

Continue Processes the program up to the next active dynamic or static

break point. If no further breakpoints exists, the system executes the

report in its entirety without stopping.

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To delete a dynamic breakpoint , place the cursor in a line and choose

BreakpointSet/Delete all.Deleting this breakpoint is also possible by double clicking theappropriate line.

From within the editor, deleting the dynamic breakpoint is done by the

following steps.

Choose UtilitiesBreakpointsDisplay.The System will list all the breakpoints.Select one or more breakpoint.Choose Delete individual .

Temporary deleting of Dynamic breakpoint is possible by selecting the

appropriate line and select Breakpoint Deactivate/Activate.

Debugging


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Deleting Watchpoints.

Watch points are special break points set for specific fields. Only one

watch can be set at a time.

To remove a watch point , the following steps will do.

Choose F to enter the field display view.

Choose Breakpoint Delete/Set watchpoint or turn the Watchpointcheckbox off.

Displaying the Location of breakpoints.

Select Goto Breakpoints to get an overview of all existing breakpointsin a programs code.From the breakpoint display , it is possible to set or delete individual

breakpoints.

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Return Returns the debugger to where a calling program resumes

control.Can be used from within a subroutine call.

Displaying the field contents.

During the course of debugging , display of the contents of the critical

fields used in the program.To display the field view contents, enter the

variable view.This is the default Debugger view. It is possible to reach thevariable view from any of the Debuggers other five views by choosing V.

Display of the contents up to four fields or field strings possible can be

done. We can enter the field names directly in the spaces provided or

double click the field in the code display and the system lists it as avariable automatically.

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We can use the variable screen to display the contents of any system field

or all field that a program references. Also the debugger to display fields

defined in the ABAP/4 Dictionary can be used.

To display the contents of dictionary fields, we must define relevant tablein the TABLES statement of the current program.

Additionally the contents of the fields from external programs can be

displayed.

For this we need to place the name of the external program in brackets infront of the field name.

We can display the contents of the fields in either edited or hexadecimal

format. To switch to the hexadecimal display, choose the small push-

button directly following the value field. When the field is in hexadecimal,an X appears on this push-button. Other wise , the button is blank.

We can always display a whole field string. To show only certain

sections, specify the appropriate offset and length. In this case we can

switch to the hexadecimal display in order to interpret packed values.

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Field contents and the most important attributes of a selected field or

field string can also be displayed in the special field view screen.

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Displaying Internal tables.

Within the debugger , we can display the contents of an internal table by

choosing the Table function.

The system displays the Table view. Specify a table name in the Internal

table field or double click on the table. If the internal table contains a

header line, this line appears before the actual table contents and is

marked in the display by >>>>>>>.The table rows are numbered. We can

scroll through the table display using the Index field or the scroll icons. Ifwe want to see those parts of the tables that are not visible on the left or

right of the screen , use the push buttons for horizontal scrolling or

simply shift the title bar of the table.

Using the column header line, we can also change the sequence of thefields we want to see. If we remove a field name from the column header

line, then the system deletes the field from the display. If we specify an

incorrect field name, the system displays a string of question marks.

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If the space you leave to display a field is too small , the system

truncates the display and indiates this by a


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Replacing fields at Runtime.

While we are debugging a program , we might want to change the content

of specific fields to influence our programs flow. If error analysis revealsthat a field contains a wrong value , for example , we can replace the

faulty value at run time to determine if the program then runs correctly.

We can change the values of all fields , database tables (with offset) and

internal tables referenced in a report . If we alter the values of databasefields , we do not change them in the database itself , but only in the work

area ABAP/4 provides for one run of the report .The system displays an

appropriate message if any format errors occur.

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To replace the value , we can do the following steps.

1.Go to the variable display screen.

This is the Debuggers default view.2.Double click on a variable to place it in the variables display.

3.Enter a new value in the second column of the variable display next to

the appropriate field.

4.Choose the R (Replace)button.

ABAP/4 writes the new value back to the program field or fields and the

system notes the change in the

system log. If we forget to click on the R push-button , the system

ignores the values we entered.

Note: ABAP/4 accepts our entries in the contents column exactly as we

specified them. You need to pay special attention to the correct format.(

Upper or lower case , right justified output with packed numbers).

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Changing Internal Tables at Runtime

The debugger allows to manipulate the contents of an internal table

during runtime. We can delete, edit or add a row to an internal table.

Deleting a row

To delete an entry from an internal table:

1. Go to the table display screen2. Enter the table name in the internal table field.

3. Choose Enter.

The system displays the tables contents.

4.Place the cursor on the line you wish to remove from the table.5.Choose Delete.

The line disappears from the table and the system adjusts the line

numbering accordingly.

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Editing a row

The functions Modify , Insert and append are field-specific in the

Debugger and can be carried out only one field at a time.For example ,If we want to edit the following line:

LH001 FRANKFURT NEWYORK 145400 400 X,

we first need to decide which field to change.

Then the following steps must be done.

1.Place the cursor on the row and field we want to edit.

2.Choose Modify.

3.Enter a new value for the field.

4.Choose Enter.

The system updates the line and displays the new contents in the table.

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.Adding a Row

We can add a new row to an internal table by using either Append or the

Insert function. Append places the new line at the end of the table.

Insert lets us to position the line anywhere.

To add a new row to the end of the table , the following steps will do.

1.Choose append.

2.Enter a value for the first field in the line.

3.Choose Enter.

The system adds a line to the table and fills in the first field.

4.Enter the remaining fields of the line by following the procedure forediting a row as described above.

To insert a new line anywhere in the internal table ,position the cursor on

the line directly following the line where we want the new row to appear.

Then ,Choose Insert button and proceed as we want to append the line.

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.Switching to the ABAP/4 Editor

We can switch from the Debugger to ABAP/4 Editor at any time. If we

discover a program error during the debugging process , for example,wecan enter the ABAP/4 Editor to immediately correct the error in the

programs code. We can also switch back to the editor in order to set new

static break-points.

After we set static breakpoints in the editor,they are not active in the

debugger when we switch back.We must re-generate the program.Thenthe breakpoints appear in the debugger.

To return to the Editor for the program currently being debugged ,

Select Development-->ABAP/4 Editor.

Debugging

D b i


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.Releasing the Database during debugging

During debugging, the system normally suppresses the COMMIT

statement. The COMMIT statement marks the end of a logical unit ofwork(LUW).

As a result , the system locks up the database for the course of that

debugging session.

If we want to temporarily stop the program but do not want to end

session,we should release the database that in use.If we forget to release

this lock,no other user is able to modify data until we complete the test.To

release the database explicitly during break in testing , choose

Debugging -->Database -->Commit.

To undo all changes made in the database since the last COMMIT selectDebugging-->Database-->Rollback.

Debugging

7120983 16 debugging techniques

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