In WebAssembly, managing data is primarily handled through memory and tables. These form a vital part of the lower-level structure. In essence, memory holds the linear address space, or the values that your WebAssembly code can work on, while tables provide a resizable array of references to functions or objects. Together, they lay the basis for WebAssembly's robust data handling.

Memory in WebAssembly works just like in lower-level languages like C and C++. It is a contiguous, resizable array of bytes, akin to a JavaScript ArrayBuffer. This memory block can be accessed as an array of integers, with each element's size varying from 1 byte (i8 or u8) to 4 bytes (i32 or u32). It's also a common practice for modules to include an exported memory object for better efficiency when manipulating large chunks of data. For instance, a graphics-heavy web game would highly benefit from this optimization.

In the context of tables, WebAssembly allows them to be initialized and dynamically modified at run time. The only element type currently available is 'anyfunc', which means that tables can hold function references. This opens the door for versatile abstractions, such as indirect function calls and implementing function pointers.

Let's go with a basic example. Supposing you are building a dynamic page that displays various pieces of marketing content based on user behaviors, you may define a table of functions each returning the relevant content:

1#include<iostream>
2using namespace std;
3
4void showVideoAd() {
5  cout << "Showing video ad" << endl;
6}
7
8void showImageAd() {
9  cout << "Showing image ad" << endl;
10}
11
12void showDiscountOffer() {
13  cout << "Showing discount offer" << endl;
14}
15
16// the table would be implemented in WebAssembly, this is an simplified illustration
17void(*funcTable[3])() = { showVideoAd, showImageAd, showDiscountOffer };
18
19int main() {
20  // Demonstrate calling functions via the function table
21  for (int i = 0; i < 3; i++) {
22    funcTable[i]();
23  }
24}

In WebAssembly, memories and tables represent a link between the high-level JavaScript and lower-level WebAssembly world. Understanding their function provides further insight into how WebAssembly optimizes for speed and flexibility.

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#include<iostream>

using namespace std;

​

void showVideoAd() {

  cout << "Showing video ad" << endl;

}

​

void showImageAd() {

  cout << "Showing image ad" << endl;

}

​

void showDiscountOffer() {

  cout << "Showing discount offer" << endl;

}

​

// the table would be implemented in WebAssembly, this is an simplified illustration

void(*funcTable[3])() = { showVideoAd, showImageAd, showDiscountOffer };

​

int main() {

  // Demonstrate calling functions via the function table

  for (int i = 0; i < 3; i++) {

    funcTable[i]();

  }

}