The instrex.h header file

To reduce duplication and simplify the program we add some features to the header file instrex.h.

The C ++ code file (extension .cpp) is not the only file common to C ++ programs. Another type of file is called a header file, sometimes called an include file. Although the extension of the header file is usually .h, you can see that the extension is .hpp or has no extension at all. The purpose of the header file is to save declarations of other files being used. This program displays "Hello, world!" With cout on the console. However, since this program does not define cout, how does the compiler recognize what cout is? The answer is that cout is declared in the header file "iostream". When using #include lines, you need to copy everything named "iostream" in the header file to the include file. This makes the contents of the header file available in the code file.

All files have titles, but only EF contains data. The first byte of each header identifies the file type and the header contains information about the file structure. The body of EF contains information related to the application. The file is management specific or application specific, and the operating system can control access to stored data. Security features are built into the SIM card. The three file types MF, DF and EF contain security attributes. These security functions filter each execution and allow access to the requested function only to users with appropriate authority. The DF file and the EF file have different levels of access conditions. They are:

File type (using file extension and header) - File extension is associated with file type. Image files (.jpg, .bmp, .png, etc.) open graphic applications or programs. A .doc file may open MS Word or WordPad. The .txt file opens a text editor. The video file opens with the video file. However, for a variety of reasons, not all applications and files are opened based on file extensions. One of the reasons is that the application may not be installed on your computer. When file .xlsx is e-mailed to user A who does not have Excel installed on user A's machine, since the associated application is not installed on the computer, opening the file by double-clicking on the file can not. With this in mind, many high - tech experts change file extensions to remove inspectors, but they do not know that changing file extensions does not have a file header. It contains information encoded in the file header