Helpers for reading binary file formats in C++.

read-binary-types.cpp

#include <fstream>
#include <iostream>
#include <array>

// creates a new instance of the type
// and reads data into it. Good for single
// value types.
template<typename T>
T STLParser::readBinary(std::ifstream& ifs) {
	T out;
	ifs.read(
		reinterpret_cast<char*>(&out),
		sizeof(T)
	);
	return out;
}

// reads a series of binary values
// into an array with a given type.
// Should be size and type safe.
template<typename T, size_t size>
void readBinaryArray(
	std::ifstream& ifs,
	std::array<T,size>& data
) {
	ifs.read(
		reinterpret_cast<char*>(&data),
		sizeof(T) * size
	);
}

int main() {
	std::string fileName = "sphere.stl";
	
	std::ifstream file { fileName, std::ios::binary };
	if(!file.is_open()) {
		std::cerr << "Could not open file." << std::endl;
		return 1;
	}
	
	// Skipping header (80 bytes)
	for(int i = 0; i < 80; i++) {
		file.get();
	}
	
	auto triangleCount = readBinary<uint32_t>(file);
	
	std::array<float, 12> points;
	
	for(uint32_t i = 0; i < triangleCount; i++) {
		// reads 12 floats into `points`
		readBinaryArray(file, points);
		// skip the attribute data
		readBinary<uint16_t>(file);
	}
}

Hey it’s no problem. To be clear the intent of this code is to parse binary STL files which follow a consistent, well defined encoding - it’s not to deserialize data serialized by this or other C++ implementations. I would not recommend this code for such a broad purpose, but instead a more robust serialization library, perhaps protobufs or bson.