PDF stands for Portable Document Format. The main advantage of a PDF file is that once it is created it cannot be altered.
Skittles
NO
explain file,records,field ,characters (use diagram)
read: moving data from file to memory write: moving data from memory to file
Never, and the reason is that header files are not meant to be executed.
That will depend on the file itself. There may actually be a problem with the file or it could be an incompatible format. You may need to source the file again if it is meant to be in a compatible format.
Structureless files - There is no internal structure imposed on the contents of a file. Any structure desired by the user can be used.
The file extention is JPG - thus it is a (compressed) picture. The numbers are just the size of the picture - units unknown.
File encryption utilizes passwords and strings of digits to ensure file safety and security. It is meant to ensure that data cannot be compromised. There are many ways of encrypting files.
The sys file extension was developed by Microsoft. Most files that end with sys are system data files and are not meant to be viewed by the users.
Header file is a file which is meant to be included into another file during compilation. Examples: string.h, stdio.h, inttypes.h. Header pointer is a pointer to an object called header (for example header of a linked list).
PHP code can be stored in any kind of file -- the extension of the file indicates what said file contains, but may not necessarily be true. The "php" extension is used to indicate PHP which is meant for execution and presentation.