Describe how data is shared by functions in a procedure oriented programming?

Answer 1

If you are talking about procedural languages like C, then you have two options:

Declaring global variables. These can be declared in header files, which are #included in source files to gain access to the shared data variable. Another way is to define a variable in a source file, then declare it extern in the other source files that use this variable. Note that the use of global variables is risky and generally frowned-upon.

Passing variables as function arguments. Some languages make a distinction between passing by value vs by reference. In C, everything is passed by value, even the arrays you pass are passed by value (the passed value is a pointer to the zero-th element of the array).

There are other ways of course, like using shared external files (especially if the data is shared between different processes, or multiple instances of the same process), shared memory, and semaphores (which are collectively known as IPC - InterProcess Communication).

Answer 2

In procedure oriented programs, data is either global or local. Global data is accessible to any function, however this makes it extremely difficult to keep track of when and where changes are occurring. As a result, functions that operate upon the data must test the data to ensure the data is still in a valid sate. This is usually done upon entry to the function. However, in multi-threaded applications, global data can be changed at any time, and this can lead to data races when two or more threads attempt to access the same data at the same time where at least one of those threads is writing the data.

Local data is easier to keep track of because only the function in which the data is declared has access to that data. The data can still be passed to other functions, however the programmer has more control over which functions gain access. The downside of local data is that passing data between functions can have a significant runtime cost, particularly when the data is being passed to and from those functions by value rather than by reference.

Object oriented programs address these problems by encapsulating data and the functions that specifically operate upon them. Class allow programmers to define a set of data and functions as a data type. Private members of the class are only accessible to the class and its friends, protected members are also accessible to derived classes and their friends and public members are accessible to all code. This allows the programmer fine-grained control over which functions can actually access the data, vastly reducing the number of runtime-checks necessary to ensure the data remains in a valid state.

Answer 3

Stack memory

Answer 4

In procedure oriented programming a number of function s are written to accomplish these tasks. Here , data items are placed as global so that they are accessed by all the functions . Each function may have its own data. Global data are more vulnerable to an inadvertent change by a function.