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The return value from a function is provided within the function by making an assignment to an identifier with the same name as the function. [5] However, some versions of Pascal provide a special function Exit(exp); that can be used to return a value immediately from a function, or, without parameters, to return immediately from a procedure. [6]
The true command is sometimes substituted with the very similar null command, [1] written as a single colon (:).The null command is built into the shell, and may therefore be more efficient if true is an external program (true is usually a shell built in function).
When a command is terminated by a signal whose number is N, a shell sets the variable $? to a value greater than 128. Most shells use 128+N, while ksh93 uses 256+N. If a command is not found, the shell should return a status of 127. If a command is found but is not executable, the return status should be 126. [2]
Indeed, the (command-line) shell encapsulates the operating system kernel. These are also sometimes referred to as "wrappers". [2] In expert systems, a shell is a piece of software that is an "empty" expert system without the knowledge base for any particular application. [16]
Python sets are very much like mathematical sets, and support operations like set intersection and union. Python also features a frozenset class for immutable sets, see Collection types. Dictionaries (class dict) are mutable mappings tying keys and corresponding values. Python has special syntax to create dictionaries ({key: value})
Many computer protocols, such as telnet, include a NOP command that a client can issue to request a response from the server without requesting any other actions. Such a command can be used to ensure the connection is still alive or that the server is responsive. A NOOP command is part of the following protocols (this is a partial list): telnet ...
The keyword Sub is used to return no value and Function to return a value. When used in the context of a class, a procedure is a method. [27] Each parameter has a data type that can be specified, but if not, defaults to Object for later versions based on .NET and variant for VB6. [28]
In the C standard library, the character-reading functions such as getchar return a value equal to the symbolic value (macro) EOF to indicate that an end-of-file condition has occurred. The actual value of EOF is implementation-dependent and must be negative (it is commonly −1, such as in glibc [2]). Block-reading functions return the number ...