inputwidth.cpp

来自「C语言数值算法程序大全（第二版）,课本文件」· C++ 代码 · 共 26 行

//: C04:InputWidth.cpp
// From "Thinking in C++, 2nd Edition, Volume 2"
// by Bruce Eckel & Chuck Allison, (c) 2003 MindView, Inc.
// Available at www.BruceEckel.com.
// Shows limitations of setw with input
#include <cassert>
#include <cmath>
#include <iomanip>
#include <limits>
#include <sstream>
#include <string>
using namespace std;

int main() {
  istringstream is("one 2.34 five");
  string temp;
  is >> setw(2) >> temp;
  assert(temp == "on");
  is >> setw(2) >> temp;
  assert(temp == "e");
  double x;
  is >> setw(2) >> x;
  double relerr = fabs(x - 2.34) / x;
  assert(relerr <= numeric_limits<double>::epsilon());
} ///:~