Excel 2003 Vba Error Handler
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three flavors: compiler errors such as undeclared variables that prevent your code from compiling; user data entry error such as a user entering a negative value where only a excel vba error handler only works once positive number is acceptable; and run time errors, that occur when VBA excel vba global error handler cannot correctly execute a program statement. We will concern ourselves here only with run time errors. Typical run time errors
Excel Vba Error Handling
include attempting to access a non-existent worksheet or workbook, or attempting to divide by zero. The example code in this article will use the division by zero error (Error 11) when we
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want to deliberately raise an error. Your application should make as many checks as possible during initialization to ensure that run time errors do not occur later. In Excel, this includes ensuring that required workbooks and worksheets are present and that required names are defined. The more checking you do before the real work of your application begins, the more stable your application will be. excel vba error 1004 It is far better to detect potential error situations when your application starts up before data is change than to wait until later to encounter an error situation. If you have no error handling code and a run time error occurs, VBA will display its standard run time error dialog box. While this may be acceptable, even desirable, in a development environment, it is not acceptable to the end user in a production environment. The goal of well designed error handling code is to anticipate potential errors, and correct them at run time or to terminate code execution in a controlled, graceful method. Your goal should be to prevent unhandled errors from arising. A note on terminology: Throughout this article, the term procedure should be taken to mean a Sub, Function, or Property procedure, and the term exit statement should be taken to mean Exit Sub, Exit Function, or Exit Property. The term end statement should be taken to mean End Sub , End Function, End Property, or just End. The On Error Statement The heart of error handling in VBA is the On Error statement. This statement instructs VBA
the wrong time. The application may crash. A calculation may produce unexpected results, etc. You can predict some of these effects and take appropriate actions. Some other problems are not under your control. Fortunately, both Microsoft Excel and
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the VBA language provide various tools or means of dealing with errors. Practical Learning:Introducing Error excel vba error handling type mismatch Handling Open the Georgetown Dry Cleaning Services1 spreadsheet and click the Employees tab Click the Payroll tab Click the TimeSheet tab To save excel vba error handling find method the workbook and prepare it for code, press F12 Specify the folder as (My) Documents In the Save As Type combo box, select Excel Macro-Enabled Workbook Click Save Introduction to Handling Errors To deal with errors in your http://www.cpearson.com/excel/errorhandling.htm code, the Visual Basic language provides various techniques. One way you can do this is to prepare your code for errors. When an error occurs, you would present a message to the user to make him/her aware of the issue (the error). To prepare a message, you create a section of code in the procedure where the error would occur. To start that section, you create a label. Here is an example: Private Sub cmdCalculate_Click() ThereWasBadCalculation: End Sub http://www.functionx.com/vbaexcel/Lesson26.htm After (under) the label, you can specify your message. Most of the time, you formulate the message using a message box. Here is an example: Private Sub cmdCalculate_Click() ThereWasBadCalculation: MsgBox "There was a problem when performing the calculation" End Sub If you simply create a label and its message like this, its section would always execute: Private Sub cmdCalculate_Click() Dim HourlySalary As Double, WeeklyTime As Double Dim WeeklySalary As Double ' One of these two lines could produce an error, such as ' if the user types an invalid number HourlySalary = CDbl(txtHourlySalary) WeeklyTime = CDbl(txtWeeklyTime) ' If there was an error, the flow would jump to the label WeeklySalary = HourlySalary * WeeklyTime txtWeeklySalary = FormatNumber(WeeklySalary) ThereWasBadCalculation: MsgBox "There was a problem when performing the calculation" End Sub To avoid this, you should find a way to interrupt the flow of the program before the label section. One way you can do this is to add a line marked Exit Sub before the label. This would be done as follows: Private Sub cmdCalculate_Click() Dim HourlySalary As Double, WeeklyTime As Double Dim WeeklySalary As Double ' One of these two lines could produce an error, such as ' if the user types an invalid number HourlySalary = CDbl(txtHourlySalary) WeeklyTime = CDbl(txtWeeklyTime) ' If there was an error, the flow would jump to the label WeeklySalary = HourlySalary * WeeklyTime txtWeeklySalary = FormatNumb
generally put more focus on the coding part and getting the desired result but during this process we forget an important thing i.e. Error handling. Error handling is an important part of every code and VBA On Error Statement is an easy way for http://www.exceltrick.com/formulas_macros/vba-on-error-statement/ handling unexpected exceptions in Excel Macros. A well written macro is one that includes proper exception handling routines to catch and tackle every possible error. Error handling is important because in case of any unexpected exceptions your code doesn’t break. Even http://www.excel-easy.com/vba/examples/error-handling.html if any fatal unexpected error occurs in the code then also you should ensure that the code should terminate gracefully. Definition of VBA On Error Statement: On Error statement instructs VBA Compiler, what to do in case any runtime exception are thrown. vba error Syntax of On Error Statement: Basically there are three types of On Error statement: On Error Goto 0 On Error Resume Next On Error Goto
execution at a specified line upon hitting an error. Situation: Both programs calculate the square root of numbers. Square Root 1 Add the following code lines to the 'Square Root 1' command button. 1. First, we declare two Range objects. We call the Range objects rng and cell. Dim rng As Range, cell As Range 2. We initialize the Range object rng with the selected range. Set rng = Selection 3. We want to calculate the square root of each cell in a randomly selected range (this range can be of any size). In Excel VBA, you can use the For Each Next loop for this. Add the following code lines: For Each cell In rng Next cell Note: rng and cell are randomly chosen here, you can use any names. Remember to refer to these names in the rest of your code. 4. Add the following code line to the loop. On Error Resume Next 5. Next, we calculate the square root of a value. In Excel VBA, we can use the Sqr function for this. Add the following code line to the loop. cell.Value = Sqr(cell.Value) 6. Exit the Visual Basic Editor and test the program. Result: Conclusion: Excel VBA has ignored cells containing invalid values such as negative numbers and text. Without using the 'On Error Resume Next' statement you would get two errors. Be careful to only use the 'On Error Resume Next' statement when you are sure ignoring errors is OK. Square Root 2 Add the following code lines to the 'Square Root 2' command button. 1. The same program as Square Root 1 but replace 'On Error Resume Next' with: On Error GoTo InvalidValue: Note: InvalidValue is randomly chosen here, you can use any name. Remember to refer to this name in the rest of your code. 2. Outside the For Each Next loop, first add the following code line: Exit Sub Without this line, the rest of the code (error code) will be executed, even if there is no error! 3. Excel VBA continues execution at the line starting with 'InvalidValue:' upon hitting an error (don't forget the colon). Add the following code line: InvalidValue: 4. We keep our error code simple for now. We display a MsgBox with some text and the address of the cell where the error occurred. MsgBox "can't calculate square root at cell " & cell.Address 5. Add the following line to instruct Excel VBA to resum