A computer error is any visible sign that describes any issue that arises unexpectedly that cause a computer not to function properly. Computers can encounter either software errors or hardware errors.
We can also distinguish between the following types of errors: Syntax errors: errors due to the fact that the syntax of the language is not respected. Semantic errors: errors due to an improper use of program statements. Logical errors: errors due to the fact that the specification is not respected.
The 7 Most Common Types of Errors in Programming and How to Avoid Them
- Syntax Errors. Just like human languages, computer languages have grammar rules. …
- Logic Errors. Logic errors can be the hardest to track down. …
- Compilation Errors. …
- Runtime Errors. …
- Arithmetic Errors. …
- Resource Errors. …
- Interface Errors.
How to find and fix programming errors
Error, Errors, Everywhere
Suppose you are trying to write a SAS/IML program that computes the factorial of a number, n. The following statements might represent your initial attempt:
|proc iml; n = 200; fact = 1 do k = 1 to n; fact = fact * n; end; print fact;|
The program contains three errors—one of each kind—for an impressive error-to-line ratio of 50%. Can you find the three errors?
A parse-time error occurs when the syntax of the program is incorrect. (This is also called a compile-time error for languages such as C/C++ and Java.) A parse-time error is the easiest error to correct because the parser (or compiler) tells you exactly what is wrong and on what line the problem occurs.
Common parse-time errors include mistyping a statement, forgetting a semicolon, or failing to close a set of parentheses. In strongly typed languages such as C/C++, Java, and IMLPlus, you also get a parse-time error when you try to use a variable of one type when a different type is expected. For example, it is an error to pass an integer into a function that is expecting an array or an object of a class.
In PROC IML, parse-time errors are reported in the SAS log. In SAS/IMLStudio you can select Program > Check Syntax to check your program for parse-time errors.
For the example program, SAS/IML Studio reports the following error:
ERROR: The program contains a syntax error. IMLPlus did not expect the following text: do (4, 1)
There is nothing wrong with the DO statement on Line 4, but there is a missing semicolon at the end of Line 3. As a result, the IMLPlus parser sees the statement fact = 1 do k = 1 to n; which is invalid syntax.
Fix #1: To fix the parse-time error, insert a semicolon at the end of Line 3.
A run-time error does not occur until the program is actually run. Common SAS/IML run-time errors include adding matrices that are different sizes, taking the logarithm of a negative value, and using the matrix index operator to specify indices that do not exist.
SAS/IML Studio has some nice features for finding and fixing parse-time and run-time errors. When you run the revised test program, the SAS log reports the following error:
»ERROR: Overflow error in *.
You can jump directly to the location of the error in a program window, by doing the following:
- Right-click the error message in the Error Log window. A pop-up menu is displayed.
- Select Go to Source.
SAS/IML Studio positions the cursor in the Program window at the location of the error. By using the techniques in the previous blog post and by using the Auxiliary Input window to interrogate the value of k at the time of the error, you discover that the numerical overflow error occurs when k is 134. “Hmmmm,” you think to yourself, “200! is a big number (in fact, it’s 374 digits long!), perhaps I should try a more manageable value.”
Fix #2: To fix the run-time error, decrease the value of n. For definiteness, set n=20.
By far, the most difficult error to find is the logical error. A program can have a logical error due to a mistyped formula or due to an incorrectly implemented algorithm. The savvy statistical programmer can use the following techniques to find and eliminate logical errors:
- Test the program on simple cases for which the result of the program is known.
- Break down the program into a sequence of basic steps and independently test each component.
- Favor clarity and simplicity when you initially write the program. After the program is working, you can profile the code and go back to optimize sections that are performance bottlenecks.
If you run the program with n=20, the program prints the following value:
Is this the correct value for 20!? I don’t know. Maybe I should test my program on a simpler case? I know that 3!=6, so I’ll change the value of n to n=3 and re-run the program. The program prints the following value:
I know that 27 isn’t correct, and I recognize that 27 = 33 so I review the logic of my program statements. Sure enough, I’ve made a mistake. The statement inside the loop should involve the counter k, not the value n.
Fix #3: To fix the logical error, the statement inside the loop should be fact = fact * k.
fact = fact(20);
It doesn’t get much simpler than that.
How to troubleshoot Windows Installer errors
When you install, uninstall, or update a program on a Windows-based computer, you may receive one of the following error messages.
Error message 1
The Windows Installer Service could not be accessed.
Error message 2
Windows Installer Service couldn’t be started.
Error message 3
Could not start the Windows Installer service on Local Computer. Error 5: Access is denied.
To fix this problem automatically, run the “Fix problems that programs cannot be installed or uninstalled” troubleshooter to repair issues that block program installation or removal because of corrupted registry keys.
Important To perform many of the methods and steps in this article, you must be logged on to your computer as an administrator.
Runtime Error 5 – What Is It?
Runtime Error 5 is one of those errors that Windows users encounter at least once in their life.
Generally, when Runtime Error 5 occurs, the message that appears says ‘Invalid Procedure Call or Argument’. Runtime Error 5 occurs because the Quality Analyst function that resides within the Operating System behaves in an abnormal manner and the user receives a warning.
As explained above, Runtime Error 5 is caused because of the unexplained behavior of the Quality Analyst function.
The problem occurs when the function is lost and is not mapped to any drive. As a result, Windows is unable to find and load it and displays the error message. Runtime Error 5 is also caused by other reasons listed below as follows.
- When files of programs like Visual Basic use bad entries in the registry.
- When a user attempts to load Internet Explorer and a global cash of browser occurs, this also causes Runtime Error 5.
Since these types of errors can easily be fixed, it is strongly advised that a user takes the necessary actions to keep them from occurring in future.
Further Information and Manual Repair
Some instructions for users to fix Runtime Error 5 as soon as it appears are listed below as follows.
- Users are recommended to restart their computers. However, prior to doing so, it is advised that any programs that are opened are closed and work is saved to prevent data loss. Once the computer restarts, users should load the program that triggered Runtime Error 5 once again to determine whether or not the error recurs.
- If the problem persists, the best approach is to uninstall the program causing the error. This can be accomplished by going to the ‘Control Panel’ and selecting the ‘Add/Remove programs’ option if one is using Windows XP or Windows 95. However, if a user is running Windows 7, the same task can be accomplished in the ‘Program and Features’ option. If there’s any option that allows you to clear personal settings and preferences, the box should be checked.
- Now reinstall the program using the latest version of installer to stop encountering this error. Use any patch for the program if available. Run installer while following the instructions on screen. Check the default settings as well. It is suggested to instantly install any patches if available.
- Another advice is to simultaneously press ‘Ctrl, Shift and Esc’. Windows task manager will appear. Go to the “processes” tab and select a process that doesn’t look familiar to you. Note the filename and click on the ‘End Process’ button. Load the program again and find out if the error occurs. Once the program causing the error is identified, the user can perform the steps listed above to resolve the problem.
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