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C Programming: Pointer Anology (lemm.ee)

submitted 1 day ago by Ryick@lemm.ee to c/programming@programming.dev

12 comments fedilink hide all child comments

Pointers in C can often be difficult to understand—I certainly had a learning curve and am continuing to learn. However, I had a thought that may help some by comparing a common experience and wanted to share.

A pointer in C behaves just like a word in any spoken language which refers to a physical object or multiple objects and the uniqueness of each object (e.g Skippy the dog, Mittens and Tiger the cats, fork number 5). The word itself does not contain the physical object and its uniqueness but only communicates the existence of the physical object and its uniqueness. The pointer itself does not contain the physical address and its value but only communicates the existence of the physical address and its value.

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[–] Ryick@lemm.ee 1 points 20 hours ago (1 children)

Let’s make an agreement that the English word “coffee” now means 65. The reference of any word within any language only exists because we make an agreement with ourselves or with others for what a particular set of symbols gives reference to. Without an agreement, all the symbols we use mean nothing more than an arbitrary scratch on a table.

A pointer is the word, which means nothing by itself other than a grouping of letters exist, and the reference to an address is the reference to an object, which exists independently from the object—a reference to a fictional object can exist and a real object can exist without a reference.

[–] Sunsofold@lemmings.world 1 points 15 hours ago

Human language has 2 layers. Signifier and signified. Computers have 3. Signifier (variable name), memory address, (no human analog) and signified. (stored value) A pointer would be a signifier (word) for which the signified is the non-existent human analog to a memory address. You can have a word that refers to a thing that doesn't exist (e.g. unicorn) but it won't help the analogy.

In your example, the signifier 'coffee' is akin to a variable name. It is a signifier that dereferences to a value within the scope of our agreement. We can agree it holds the stored value of 65, allowing us to say something like butter = coffee - 60, bring me 'butter' eggs, but we don't have a memory address system so it's not the same process as a computer.

For a computer, there is a middle step to a variable dereference. It sees 'coffee' and first looks at the table of references, finds the variable 'coffee' has it's value stored at address 1 ['coffee':1, 'butter':88, 'unicorn':73] and then pulls the value (65) from the memory at address 1. A pointer would be another variable, such as '*monkey' (e.g. *monkey = &coffee, which can be read as "pointer monkey shall hold the value of the address at which coffee is stored") which would be added into the reference table as a variable stored at another address, say address 2, and would store in address 2 a value of (1).

word        address       value
coffee      1                65
*monkey     2                1

Language just doesn't have the analogous concept.