In general terms, descriptors are some attributes of objects for which the corresponding behavior is defined. When accessing them, they receive, install or delete the specified attributes from the dictionary. In simple terms, these are special keywords that define the behavior of an object, its properties or structure. The article will consider several options for descriptors. This will allow a more accurate understanding of their essence and purpose.
HTML
In the hypertext markup language that is used to create static web pages, descriptors are nothing more than tags. In this environment, they act as labels, due to which the text placed between them is displayed in a certain way. Thus, the design and arrangement of elements on the page is formed.
As a rule, the specificity of the language determines the presence of an opening descriptor and a closing one. Everything in between is subject to change.
A descriptor can have attributes, that is, certain properties. Their syntax is as follows: attribute name = its value.
Subject to the general logic, descriptors in HTML are identification tags of objects. With their help, you can control the appearance, interact with the page and assign special values to it.
X86 architecture
In processors, descriptors are a special structure by which various transitions are made. Its structure looks like this:
- Bias. May shift the code procedure.
- Selector. Reflects a kind of label where the procedure should go.
- Number of parameters.
- Access rights.
Java
Java EE has the concept of a deployment descriptor. It determines how the servlet will be deployed. In essence, this is a configuration file containing settings, properties, and hardware requirements.
In web applications, such a file by the rules should be called web.xml and located in a specific folder.
File descriptors
In operating systems, to work with files, you must first access them. This can be done through a file descriptor. In this example, it acts as a kind of label, which denotes the process that created the input-output stream.
The Windows operating system allows you to access the descriptor using the CreateFile function. It can be further used when working with the desired file.
Unix systems use naming conventions for the file descriptor. 0 - standard input of the terminal process, 1 - its output, 2 - diagnostic flow. In addition to numeric representations, you can use symbolic constants defined by the specification.
Window handle
After any window is created in the system, a specific descriptor is assigned to it. The data types used in it are HWND. When creating an application, the programmer needs to use them correctly to access the window elements.
A program can get a handle by accessing the FindWindow function. She will be able to find it and return the descriptor value by the name of the class or window object.
To check if the authentication has passed correctly, it is worth using the IsWindow function.
Error number 1400
This problem is common in the Windows family of operating systems. When it appears, there may be a short description with it - an invalid window handle. But such a wording may also occur - “Error_invalid_window_handle” or 0x578.
How to fight and what does an invalid descriptor mean? Depending on the context of the object, different measures need to be taken.
In any case, you should immediately go over the standard measures taken to all problems with the system:
- computer reboot;
- start and scan errors using the system file integrity check utility;
- scan your computer for viruses.
If the basic steps did not help, then it may be worth uninstalling and reinstalling the application that causes the crash.
Another reliable way to quickly restore the system is to roll back using standard tools. After using System Restore, it will return to the last valid backup, provided that it was previously created.
When an error may occur
In most cases, an invalid descriptor error is caused due to flaws in the installed software. Therefore, it is worthwhile to carefully monitor what appears on the computer from the software. It is also necessary to periodically update all available software and monitor its status. At the same time, it is worth arming yourself with good antivirus software.
Conclusion
The article presented the general principles of operation of descriptors in various programming languages and operating systems, their functions, properties and types. As a rule, this term is mainly used by programmers and developers to identify objects and elements for subsequent access to them and management.
And it also became clear that this is an invalid descriptor. As it turned out, this is a common problem in the Windows environment, in most cases solved by simple manipulations.