Using emscripten to compile c++ code to javascript for making the sum of two numbers.Practice

Question

I want to make a short example to understand how emscripten works. I want to make a html where I could add two numbers in two different text box. I also added a button and a third text box where the result should be printed after I introduce two numbers above and I pressed the button.

Did You try this tutorial? (kripken.github.io/emscripten-site/docs/getting_started/…) — Robert Andrzejuk
– Robert Andrzejuk, Commented Aug 21, 2018 at 11:52

HugoTeixeira · Accepted Answer · 2018-08-21 15:09:01Z

2

I see a few issues with your project. First, I think you should tag the C++ functions with EMSCRIPTEN_KEEPALIVE like this:

int EMSCRIPTEN_KEEPALIVE int_sum_of_two_numbers(int number1, int number2)
{
    int sum;
    sum = number1 + number2;
    return sum; 
}

From the Emscripten documentation:

If your function is used in other functions, LLVM may inline it and it will not appear as a unique function in the JavaScript. Prevent inlining by defining the function with EMSCRIPTEN_KEEPALIVE

That allows Javascript code to find your C++ functions.

Besides that, the command you use to compile your project seems to have an extra underscore _ character when you mention the exported functions _int_sum_of_two_numbers => int_sum_of_two_numbers. So you should have used:

EXPORTED_FUNCTIONS='["int_sum_of_two_numbers"]'

As a final note, you could leave the main() function empty. The code inside that function is irrelevant to your web application.

I wrote an article a while ago about integrating WebAssembly with Angular and it is very similar to what you are trying to achieve. I think this would be worth reading.

edited Aug 21, 2018 at 15:09

answered Aug 21, 2018 at 15:02

HugoTeixeira

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1 Comment

HugoTeixeira Over a year ago

If you still have issues, then maybe you should add more information about your HTML page. I don't see any reference to the generated wasm file in that code.

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