#ifdef _MSC_VER
#define _SECURE_SCL 0
#define _CRT_SECURE_NO_DEPRECATE 1
#define WIN32_LEAN_AND_MEAN
#define VC_EXTRALEAN
#define NOMINMAX
#endif
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <ctime>
#include <cmath>
#include <iostream>
#include <string>
#include <vector>
#include <iomanip>
#include <sstream>
#include <boost/lexical_cast.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix_core.hpp>
#include <boost/spirit/include/phoenix_operator.hpp>
#include "cycle.h"
static const size_t N = 100000;
static const size_t R = 7;
void PrintStats(std::vector<double> timings) {
double fastest = std::numeric_limits<double>::max();
std::cout << std::fixed << std::setprecision(2);
std::cout << "[";
for (size_t i = 1 ; i<timings.size()-1 ; ++i) {
fastest = std::min(fastest, timings[i]);
std::cout << timings[i] << ",";
}
std::cout << timings.back();
std::cout << "]";
double sum = 0.0;
for (size_t i = 1 ; i<timings.size() ; ++i) {
sum += timings[i];
}
double avg = sum / static_cast<double>(timings.size()-1);
sum = 0.0;
for (size_t i = 1 ; i<timings.size() ; ++i) {
timings[i] = pow(timings[i]-avg, 2);
sum += timings[i];
}
double var = sum/(timings.size()-2);
double sdv = sqrt(var);
std::cout << " with fastest " << fastest << ", average " << avg << ", stddev " << sdv;
}
double naive(const char *p) {
double r = 0.0;
bool neg = false;
if (*p == ‘-‘) {
neg = true;
++p;
}
while (*p >= ‘0‘ && *p <= ‘9‘) {
r = (r*10.0) + (*p - ‘0‘);
++p;
}
if (*p == ‘.‘) {
double f = 0.0;
int n = 0;
++p;
while (*p >= ‘0‘ && *p <= ‘9‘) {
f = (f*10.0) + (*p - ‘0‘);
++p;
++n;
}
r += f / std::pow(10.0, n);
}
if (neg) {
r = -r;
}
return r;
}
int main() {
std::vector<std::string> nums;
nums.reserve(N);
for (size_t i=0 ; i<N ; ++i) {
std::string y;
if (i & 1) {
y += ‘-‘;
}
y += boost::lexical_cast<std::string>(i);
y += ‘.‘;
y += boost::lexical_cast<std::string>(i);
nums.push_back(y);
}
{
double tsum = 0.0;
std::vector<double> timings;
timings.reserve(R);
for (size_t r=0 ; r<R ; ++r) {
ticks start = getticks();
for (size_t i=0 ; i<nums.size() ; ++i) {
double x = naive(nums[i].c_str());
tsum += x;
}
ticks end = getticks();
double timed = elapsed(end, start);
timings.push_back(timed);
}
std::cout << "naive: ";
PrintStats(timings);
std::cout << std::endl;
std::cout << tsum << std::endl;
}
{
double tsum = 0.0;
std::vector<double> timings;
timings.reserve(R);
for (size_t r=0 ; r<R ; ++r) {
ticks start = getticks();
for (size_t i=0 ; i<nums.size() ; ++i) {
double x = atof(nums[i].c_str());
tsum += x;
}
ticks end = getticks();
double timed = elapsed(end, start);
timings.push_back(timed);
}
std::cout << "atof(): ";
PrintStats(timings);
std::cout << std::endl;
std::cout << tsum << std::endl;
}
{
double tsum = 0.0;
std::vector<double> timings;
timings.reserve(R);
for (size_t r=0 ; r<R ; ++r) {
ticks start = getticks();
for (size_t i=0 ; i<nums.size() ; ++i) {
double x = strtod(nums[i].c_str(), 0);
tsum += x;
}
ticks end = getticks();
double timed = elapsed(end, start);
timings.push_back(timed);
}
std::cout << "strtod(): ";
PrintStats(timings);
std::cout << std::endl;
std::cout << tsum << std::endl;
}
{
double tsum = 0.0;
std::vector<double> timings;
timings.reserve(R);
for (size_t r=0 ; r<R ; ++r) {
ticks start = getticks();
for (size_t i=0 ; i<nums.size() ; ++i) {
double x = 0.0;
sscanf(nums[i].c_str(), "%lf", &x);
tsum += x;
}
ticks end = getticks();
double timed = elapsed(end, start);
timings.push_back(timed);
}
std::cout << "sscanf(): ";
PrintStats(timings);
std::cout << std::endl;
std::cout << tsum << std::endl;
}
{
double tsum = 0.0;
std::vector<double> timings;
timings.reserve(R);
for (size_t r=0 ; r<R ; ++r) {
ticks start = getticks();
for (size_t i=0 ; i<nums.size() ; ++i) {
double x = boost::lexical_cast<double>(nums[i]);
tsum += x;
}
ticks end = getticks();
double timed = elapsed(end, start);
timings.push_back(timed);
}
std::cout << "lexical_cast: ";
PrintStats(timings);
std::cout << std::endl;
std::cout << tsum << std::endl;
}
{
using boost::spirit::qi::double_;
using boost::spirit::qi::parse;
double tsum = 0.0;
std::vector<double> timings;
timings.reserve(R);
for (size_t r=0 ; r<R ; ++r) {
ticks start = getticks();
for (size_t i=0 ; i<nums.size() ; ++i) {
double x = 0.0;
char const *str = nums[i].c_str();
parse(str, &str[nums[i].size()], double_, x);
tsum += x;
}
ticks end = getticks();
double timed = elapsed(end, start);
timings.push_back(timed);
}
std::cout << "spirit qi: ";
PrintStats(timings);
std::cout << std::endl;
std::cout << tsum << std::endl;
}
{
double tsum = 0.0;
std::vector<double> timings;
timings.reserve(R);
for (size_t r=0 ; r<R ; ++r) {
ticks start = getticks();
for (size_t i=0 ; i<nums.size() ; ++i) {
std::istringstream ss(nums[i]);
double x = 0.0;
ss >> x;
tsum += x;
}
ticks end = getticks();
double timed = elapsed(end, start);
timings.push_back(timed);
}
std::cout << "stringstream: ";
PrintStats(timings);
std::cout << std::endl;
std::cout << tsum << std::endl;
}
{
double tsum = 0.0;
std::vector<double> timings;
timings.reserve(R);
for (size_t r=0 ; r<R ; ++r) {
ticks start = getticks();
std::istringstream ss;
for (size_t i=0 ; i<nums.size() ; ++i) {
ss.str(nums[i]);
ss.clear();
double x = 0.0;
ss >> x;
tsum += x;
}
ticks end = getticks();
double timed = elapsed(end, start);
timings.push_back(timed);
}
std::cout << "stringstream reused: ";
PrintStats(timings);
std::cout << std::endl;
std::cout << tsum << std::endl;
}
}
