Why was C introduced the pointer to array syntax?

Question

C++ / C#

Good afternoon!
When should you use a pointer to an array?
Taken from SI-TEST Section 5 - Data Declaration.

Answer 1

For example, in order not to pass the entire array to the function, but only a pointer to it, thereby avoiding creating a copy of the array, reducing memory consumption and function call time

Answer 2

Because it's convenient :) There are complex data types - structures, unions, which are full of pointers to other pointers, etc. Very often, data objects of this type are aggregated into arrays and addressed by pointers - you get one pointer and you can iterate over a huge array.
C is a system language and get as a value a pointer that addresses an array containing pointers to elements, each of which is a pointer to something you can finally work with - easily :D

Answer 3

for example, to pass by reference rather than by value. This is required:
a. when the array can and must change during the execution of the function;
b. when there are 100,000,000,000,000,000,000 (10^20) values ​​in the array. Passing such arrays to functions by value somewhat slows down the program;
in. your choice (write in the comments).

Answer 4

To begin with, the question is why the concept of an array was introduced into the language, and not left with pointers - because typing is good. Those. at the compilation stage, it will be possible to understand whether the correct variables were passed to the function / method, and you can also find out which method to use (methods with the same name and different types of parameters, plus C ++ templates in the piggy bank)
Accordingly, in order not to transfer the entire array as a copy into methods, introduced the concept of a link (it is not only defined for arrays, but also for any objects)

Answer 5

Imagine, for example, that you have a point that is described by an array of its coordinates:
And then you make an array of such points:
And then you output them one by one:

Point2D *p, *q;

for (p = array, q = p + 5; p < q; p++) {
    print_point(*p);
}

But it is written a little differently - and you already get a straight line:

typedef struct {
    Point2D *pt1;
    Point2D *pt2;
} Line2D;

Why are there pointers here? Yes, because they eat less memory than arrays of numbers. So one straight line eats 8 bytes, and without pointers it would eat 16 bytes. And if there were a straight line in three-dimensional space, then it would also take 8 bytes, and without pointers - 24 bytes.
The code went on:

the code

#include <stdio.h>

typedef int Point2D[2];

typedef struct {
    Point2D *pt1;
    Point2D *pt2;
} Line2D;

void print_point(Point2D p)
{
    printf("(%d,%d)\n", p[0], p[1]);
}

void print_line(Line2D l)
{
    printf("Line[\n");
    print_point(*l.pt1);
    print_point(*l.pt2);
    printf("Line]\n");
}

int main(void)
{
    Point2D array[5] = {{1, 2}, {3, 4}, {5, 6}};
    Point2D *p, *q;
    Line2D l;

    for (p = array, q = p + 5; p < q; p++) {
        print_point(*p);
    }

    l.pt1 = array;
    l.pt2 = array + 2;
    print_line(l);

    return 0;
}

Вывод

[[email protected] c]$ .ansi t.c -o t
[[email protected] c]$ ./t
(1,2)
(3,4)
(5,6)
(0,0)
(0,0)
Line[
(1,2)
(5,6)
Line]
[[email protected] c]$

As you can see, without this possibility, the language would have been much more limited and would have died back in the 80s.