indexingvsat.cpp

来自「很经典的书籍」· C++ 代码 · 共 44 行

//: C07:IndexingVsAt.cpp
// Comparing "at()" to operator[]
#include <ctime>
#include <deque>
#include <iostream>
#include <vector>
#include "../require.h"
using namespace std;

int main(int argc, char* argv[]) {
  long count = 1000;
  int sz = 1000;
  if(argc >= 2) count = atoi(argv[1]);
  if(argc >= 3) sz = atoi(argv[2]);
  vector<int> vi(sz);
  clock_t ticks = clock();
  for(int i1 = 0; i1 < count; i1++)
    for(int j = 0; j < sz; j++)
      vi[j];
  cout << "vector[] " << clock() - ticks << endl;
  ticks = clock();
  for(int i2 = 0; i2 < count; i2++)
    for(int j = 0; j < sz; j++)
      vi.at(j);
  cout << "vector::at() " << clock()-ticks <<endl;
  deque<int> di(sz);
  ticks = clock();
  for(int i3 = 0; i3 < count; i3++)
    for(int j = 0; j < sz; j++)
      di[j];
  cout << "deque[] " << clock() - ticks << endl;
  ticks = clock();
  for(int i4 = 0; i4 < count; i4++)
    for(int j = 0; j < sz; j++)
      di.at(j);
  cout << "deque::at() " << clock()-ticks <<endl;
  // Demonstrate at() when you go out of bounds:
  try {
    di.at(vi.size() + 1);
  } catch(...) {
    cerr << "Exception thrown" << endl;
  }
} ///:~