Arrays in C++

#include <iostream>
#include <array>

int main() {
    // Here we create an array 'a' that will hold exactly
    // 5 ints. The type of elements and length are both
    // part of the array's type. By default an array is
    // zero-initialized, which for ints means 0s.
    std::array<int, 5> a = {};
    std::cout << "emp:";
    for (int i : a) {
        std::cout << " " << i;
    }
    std::cout << std::endl;

    // We can set a value at an index using the
    // array[index] = value syntax, and get a value with
    // array[index].
    a[4] = 100;
    std::cout << "set:";
    for (int i : a) {
        std::cout << " " << i;
    }
    std::cout << std::endl;
    std::cout << "get: " << a[4] << std::endl;

    // The size() function returns the length of an array.
    std::cout << "len: " << a.size() << std::endl;

    // Use this syntax to declare and initialize an array
    // in one line.
    std::array<int, 5> b = {1, 2, 3, 4, 5};
    std::cout << "dcl:";
    for (int i : b) {
        std::cout << " " << i;
    }
    std::cout << std::endl;

    // C++ doesn't have a direct equivalent to Go's `...` syntax,
    // but you can use initializer lists with std::array.
    std::array<int, 5> c = {1, 2, 3, 4, 5};
    std::cout << "init list:";
    for (int i : c) {
        std::cout << " " << i;
    }
    std::cout << std::endl;

    // C++ doesn't have a direct equivalent to Go's `3: 400` syntax,
    // but you can initialize specific elements manually.
    std::array<int, 5> d = {100, 0, 0, 400, 500};
    std::cout << "manual init:";
    for (int i : d) {
        std::cout << " " << i;
    }
    std::cout << std::endl;

    // Array types are one-dimensional, but you can
    // compose types to build multi-dimensional data
    // structures.
    std::array<std::array<int, 3>, 2> twoD = {};
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < 3; j++) {
            twoD[i][j] = i + j;
        }
    }
    std::cout << "2d: ";
    for (const auto& row : twoD) {
        for (int val : row) {
            std::cout << val << " ";
        }
    }
    std::cout << std::endl;

    // You can create and initialize multi-dimensional
    // arrays at once too.
    std::array<std::array<int, 3>, 2> twoD2 = {{{1, 2, 3}, {1, 2, 3}}};
    std::cout << "2d: ";
    for (const auto& row : twoD2) {
        for (int val : row) {
            std::cout << val << " ";
        }
    }
    std::cout << std::endl;
}

This C++ code demonstrates the usage of arrays, which are implemented using the std::array container from the C++ Standard Library. The std::array provides a fixed-size array with bounds checking.

Key points in the C++ version:

We use std::array<T, N> instead of Go’s built-in array type. T is the type of elements, and N is the size of the array.
To print array contents, we use range-based for loops or regular for loops, as C++ doesn’t have a direct equivalent to Go’s fmt.Println for arrays.
The len() function in Go is replaced by the size() member function of std::array.
C++ doesn’t have the ... syntax for array initialization, but we can use initializer lists.
C++ doesn’t have a direct equivalent to Go’s 3: 400 syntax for sparse array initialization. We initialize such arrays manually.
For multi-dimensional arrays, we use nested std::array types.

When you compile and run this program, it will produce output similar to the Go version, demonstrating various ways to create, initialize, and manipulate arrays in C++.

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Arrays in C++