read_test.cpp

#define _CRT_SECURE_NO_WARNINGS
#include <fstream>
#include <chrono>
#include <limits>
#include <functional>
#include <iostream>
#include <string>
#include <cstdio>
using namespace std;
using namespace std::chrono;

template <typename T>
void time_me(T fn, string message = "") {
	auto s = high_resolution_clock::now();
	fn();
	auto e = high_resolution_clock::now();
	cout << message << duration_cast<seconds>(e - s).count() << endl;
}

void make_file() {
	time_me([] {
		ofstream file("test.dat");
		for (uint32_t c = 0; c < 1000000000; ++c) {
			file << c;
		}
		file.close();
	});
}


void ios_read() {
	time_me([] {
		ifstream file("test.dat");
		uint32_t d, x = 0;
		while (file >> d) {
			x ^= d;
		}
	}, "read ");
}

void ios_seek_read() {
	time_me([]{
		ifstream file("test.dat");
		uint32_t d, x = 0;
		while (file >> d) {
			file.seekg(static_cast<int>(file.tellg()) + 100, ios::beg);
			x ^= d;
		}
	}, "seek-read ");
}


void stdio_read() {
	time_me([] {
		FILE * f = fopen("test.dat", "r");
		uint32_t x, d = 0;
		while (fread(&x, sizeof(x), 1, f)) {
			d ^= x;
		}
		fclose(f);
	}, "stdio-read ");
}

void stdio_read_buff() {
	const int sz = 2048;
	uint32_t buff[sz];
	time_me([&buff, sz] {
		FILE * f = fopen("test.dat", "r");
		setbuf(f, NULL);
		uint32_t x, d = 0;
		int rd = 0;
		while (rd = fread(buff, sizeof(buff[0]), sz, f)) {
			for (int c = 0; c < rd; ++c) {
				d ^= buff[c];
			}
		}
		fclose(f);
	}, "stdio-manual-buff ");
}


int main() {

	ios_read();
	ios_seek_read();
	stdio_read();
	stdio_read_buff();
	
	cin.get();
	return 0;
}