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A subprogram is a piece code that is identified by a name, is given a local reference environment of its own and is able to exchange information with the rest of the code using parameters.
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what two fundamental abstraction facilities do Subprograms/Functions provide Lernen beginnen
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Process/control abstraction, Data abstraction
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explain Process/control abstraction: Lernen beginnen
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[1] Provides programmers with the ability to hide procedural details[2] Process abstraction allows us to be concerned only with a procedure’s interface[3]E. g given a procedure sort we don’t need to know the body of sort in order to use it.
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Data abstraction: allows the use of sophisticated data types without knowing how such types are implemented. Again, the aims are to separate concerns and to promote reusability and maintainability of programs.
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what is a formal parameter Lernen beginnen
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A formal parameter is a dummy variable listed in the function header and used in the function body.
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what is an actual parameter Lernen beginnen
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An actual parameter represents a value or address used in the function call statement.
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Functions may exchange info with the rest of the program by a return value or through the use of parameters. s. n value
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what are the 2 ways to bind parameters Lernen beginnen
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: by position or by keyword.
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explain parameter binding by position Lernen beginnen
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By position: The binding of actual parameters to formal parameters is by their order of appearance: the first actual parameter is bound to the first formal parameter and so forth. x=foo(3, 0); Safe and effective.
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eexplain parameter binding by keyword Lernen beginnen
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Keyword: The names of the formal and actual parameters are used Advantage: Parameters can appear in any order, thereby avoiding parameter correspondence errors. Disadvantage: User must know the formal parameters’ names.
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what is in(put) mode in referance to Parameter Passing Methods Lernen beginnen
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Formal parameters receive data from the corresponding actual parameters.
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what is out(put) mode in referance to Parameter Passing Methods Lernen beginnen
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Formal parameters transmit data to the actual parameters; or
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what is inout) mode in referance to Parameter Passing Methods Lernen beginnen
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Formal parameters receive data from the corresponding actual parameters and Formal parameters transmit data to the actual parameters
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