4 ms·

Its been 50 years so pretty much everything has been considered. In my opinion the mistake was not having arrays decay in to pointers but rather arrays should b

Its been 50 years so pretty much everything has been considered. In my opinion the mistake was not having arrays decay in to pointers but rather arrays should be pointers in the first place. An array should be seen as a number of values where with a pointer pointing at the first one. I think adding a third version of the same functionality would just complicate things further. (&p[42] is a "slice" of an array) Another thing I do not like about slices that store lengths, is that they hide memory layout from the user and that is not a very C thing to do.

uecker 4y ago
If you think about arrays as pointers, you will get a lot of things wrong, e.g. float m[10][10]; it not a an array of pointers, but a 2D dimensional array with 2D memory layout.
- quelsolaar 4y ago
  You are right, sizeof is the other big difference. I think these differences are small enough that it was a mistake separate the two. The similarities / differences do make them confusing.
  - uecker 4y ago
    How would you express a 2D memory layout with only pointers?
    - colejohnson66 4y ago
      An array of pointers to arrays? Basically, a `T**` C#'s "jagged" arrays are like this, and to get a "true" 2D array, you use different syntax (a comma in the indexer): int[][] jagged; // an array of `int[]` (i.e. each element is a pointer to a `int[]`) int[,] multidimensional; // a "true" 2D array laid out in memory sequentially // allocate the jagged array; each `int[]` will be null until allocated separately jagged = new int[][10]; Debug.Assert(jagged.All(elem => elem == null)); for (int i = 0; i < 10; i++) jagged[i] = new double[10]; // allocate the internal arrays Debug.Assert(jagged[i][j] == 0); // allocate the multidimensional array; each `int` will be `default` which is 0 // element [i,j] will be at offset `10*i + j` multiDimensional = new double[10, 10]; Debug.Assert(multiDimensional[i, j] == 0);
      - uecker 4y ago
        Yes, this is people with pre-C99 compilers that do not support variably modified types sometimes do. It is horrible (although there are some use cases).

uecker 4y ago

If you think about arrays as pointers, you will get a lot of things wrong, e.g. float m[10][10]; it not a an array of pointers, but a 2D dimensional array with 2D memory layout.

quelsolaar 4y ago
You are right, sizeof is the other big difference. I think these differences are small enough that it was a mistake separate the two. The similarities / differences do make them confusing.
- uecker 4y ago
  How would you express a 2D memory layout with only pointers?
  - colejohnson66 4y ago
    An array of pointers to arrays? Basically, a `T**` C#'s "jagged" arrays are like this, and to get a "true" 2D array, you use different syntax (a comma in the indexer): int[][] jagged; // an array of `int[]` (i.e. each element is a pointer to a `int[]`) int[,] multidimensional; // a "true" 2D array laid out in memory sequentially // allocate the jagged array; each `int[]` will be null until allocated separately jagged = new int[][10]; Debug.Assert(jagged.All(elem => elem == null)); for (int i = 0; i < 10; i++) jagged[i] = new double[10]; // allocate the internal arrays Debug.Assert(jagged[i][j] == 0); // allocate the multidimensional array; each `int` will be `default` which is 0 // element [i,j] will be at offset `10*i + j` multiDimensional = new double[10, 10]; Debug.Assert(multiDimensional[i, j] == 0);
    - uecker 4y ago
      Yes, this is people with pre-C99 compilers that do not support variably modified types sometimes do. It is horrible (although there are some use cases).