29 March, 2021

WebAssembly with C++

WebAssembly contains instructions in binary code for a virtual machchine that can be run on the web browser. I use emscripten tools to try out WebAssembly.


  1. Create C++ code hello.cpp

int main() {
  std::cout << "Hello World!\n";
  return 0;
  1. Compile the C++ file with emcc hello.cpp -o hello.html. It generates wasm, JavaScript and HTML files.

  2. See the result

Here is one more example showing a colored cube on a Canvas using SDL. I don't know how much of SDL is supported yet.


git clone https://github.com/emscripten-core/emsdk.git
cd emsdk

Update tools (on Linux):

git pull
./emsdk install latest
./emsdk activate latest
source ./emsdk_env.sh

Input Files

Using input files, here the example main.cpp uses ifstream:

#include <iostream>
#include <fstream>

int main() {
  std::ifstream infile("main.cpp");
  std::string line;

  while(std::getline(infile, line)) {
    std::cout << line << std::endl;

  return 0;

Compile with --preload-file :

emcc main.cpp -o index.html --preload-file main.cpp

See the result