Everything I wish I knew when learning C

Re:Everything I wish I knew when learning C by Joker_vD on Tuesday November 29, 2022 @06:12AM (#33786100)

Another one corner of the language where arrays actually being arrays is important is multidimensional array access:

    int arr[5][7];
    arr[3][5] = 4; // equivalent to *(*(arr + 3) + 5) = 4;

This works because (arr + 3) has type "pointer to int[7]", not "pointer to int". The resulting address computation is

    (char*)arr + 3 * sizeof(int[7]) + 5 * sizeof(int) ==
    (char*)arr + 26 * sizeof(int)

That's also another reason why types like "int [5][7][]" are legal but "int [5][][]" are not.

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Re:Everything I wish I knew when learning C by ErikCorry on Tuesday November 29, 2022 @06:51AM (#33786394)

Really, are multidimensional arrays an important part of the language?

The above code looks like it's indexing into an array of pointers. If you want a flat array, make a few inlined helper functions that do the multiplying and adding. Your code will be much cleaner and easier to understand.

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Re:Everything I wish I knew when learning C by Joker_vD on Tuesday November 29, 2022 @09:02AM (#33787661)

Of course multidimensional arrays are an important part of the language, just as the ability to have structs inside structs.

> The above code looks like it's indexing into an array of pointers. If you want a flat array, make a few inlined helper functions that do the multiplying and adding. Your code will be much cleaner and easier to understand.

It is a "flat" array already, not an array of pointers: [0]. No need to write the code that compiler generates for you already.

[0] https://godbolt.org/z/x3cPf3TvT

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Re:Everything I wish I knew when learning C by ErikCorry on Tuesday November 29, 2022 @09:39AM (#33788129)

I am aware that it's flat already.

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Re:Everything I wish I knew when learning C by int_19h on Friday December 02, 2022 @02:14PM (#33835329)

The code above does not mention any pointer types, so why would you assume that it's indexing into an array of pointers?

I can't think of any reason why get(a, i, j) is more readable than a[i][j].

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