benchmark for std::stringstream

sstest.cc

//----------------------------------------------------------------------
#include <iostream>
#include <string>
#include <sstream>
#include <vector>
#include <random>
#include <sys/time.h>
//----------------------------------------------------------------------
std::uniform_int_distribution<> rand9(0, 9);
const int TRIAL = 500000;
const int LEN = 100;
//----------------------------------------------------------------------
void
show(std::vector<std::string> &sv) {
  for (int i = 0; i < sv.size(); i++) {
    std::cout << sv[i] << std::endl;;
  }
}
//----------------------------------------------------------------------
double
myclock(void) {
  struct timeval t;
  gettimeofday(&t, NULL);
  return t.tv_sec + t.tv_usec * 1e-6;
}
//----------------------------------------------------------------------
void
test_ss(void) {
  std::mt19937 g((std::random_device())());
  g.seed(1);
  std::vector<std::string> sv;
  for (int j = 0; j < TRIAL; j++) {
    std::stringstream ss;
    for (int i = 0; i < LEN; i++) {
      ss << rand9(g);
    }
    sv.push_back(ss.str());
  }
  //show(sv);
}
//----------------------------------------------------------------------
void
test_str(void) {
  std::mt19937 g((std::random_device())());
  g.seed(1);
  std::vector<std::string> sv;
  for (int j = 0; j < TRIAL; j++) {
    std::string str;
    for (int i = 0; i < LEN; i++) {
      str.append(1, rand9(g) + '0');
    }
    sv.push_back(str);
  }
  //show(sv);
}
//----------------------------------------------------------------------
void
test_char(void) {
  std::mt19937 g((std::random_device())());
  g.seed(1);
  char str[LEN + 1];
  str[LEN] = 0;
  std::vector<std::string> sv;
  for (int j = 0; j < TRIAL; j++) {
    for (int i = 0; i < LEN; i++) {
      str[i] = rand9(g) + '0';
    }
    sv.push_back(str);
  }
  //show(sv);
}
//----------------------------------------------------------------------
void
measure(void(*pfunc)(), const char *name) {
  double st = myclock();
  pfunc();
  double t = myclock() - st;
  printf("%s %f [sec]\n", name, t);
}
//----------------------------------------------------------------------
int
main(void) {
  measure(&test_ss, "stringstream");
  measure(&test_str, "string");
  measure(&test_char, "char");
}
//----------------------------------------------------------------------