cygwin 控制台上没有错误或 cout 消息

Question

我在 Windows7 机器上安装了 cygwin，并且正在运行一些 C++ 代码。当我运行此代码时：

#include <iostream>
#include <string>
#include <fstream>
#include <time.h>
#include <math.h>
#include "Pop.h"
using namespace std;


int main() {
  ifstream in;
  ofstream out;
  cout << "something";
  out.open("res7.txt", ios::out|ios::app);
  if (out.is_open())
    out << "1\n";
  else
    cout << "unable to open res7 file";
  out.close();
  int seed = time(NULL);
  out.open("res7.txt", ios::out|ios::app);
  if (out.is_open())
    out << "2\n";
  else
    cout << "unable to open res7 file";
  out.close();
  out.open("res7.txt", ios::out|ios::app);
  if (out.is_open())
    out << "seed " << seed << '\n';
  else
    cout << "unable to open res7 file";
  out.close();
  out.open("res7.txt", ios::out|ios::app);
  if (out.is_open())
    out << "3\n";
  else
    cout << "unable to open res7 file";
  out.close();
  srand (seed);
  out.open("res7.txt", ios::out|ios::app);
  if (out.is_open())
    out << "4\n";
  else
    cout << "unable to open res7 file";
  out.close();
  double parameters[4];
  int location;
  in.open("input7.txt", ios::in);
  out.open("res7.txt", ios::out|ios::app);
  if (out.is_open())
    out << "5\n";
  else
    cout << "unable to open res7 file";
  out.close();
  return 0;
}

我在控制台上看到输出（某些内容）。但是当我运行完整的代码时：

#include <iostream>
#include <string>
#include <fstream>
#include <time.h>
#include <math.h>
#include "Pop.h"
using namespace std;


int main() {
  ifstream in;
  ofstream out;
  cout << "something";
  out.open("res7.txt", ios::out|ios::app);
  if (out.is_open())
    out << "1\n";
  else
    cout << "unable to open res7 file";
  out.close();
  int seed = time(NULL);
  out.open("res7.txt", ios::out|ios::app);
  if (out.is_open())
    out << "2\n";
  else
    cout << "unable to open res7 file";
  out.close();
  out.open("res7.txt", ios::out|ios::app);
  if (out.is_open())
    out << "seed " << seed << '\n';
  else
    cout << "unable to open res7 file";
  out.close();
  out.open("res7.txt", ios::out|ios::app);
  if (out.is_open())
    out << "3\n";
  else
    cout << "unable to open res7 file";
  out.close();
  srand (seed);
  out.open("res7.txt", ios::out|ios::app);
  if (out.is_open())
    out << "4\n";
  else
    cout << "unable to open res7 file";
  out.close();
  double parameters[4];
  int location;
  in.open("input7.txt", ios::in);
  out.open("res7.txt", ios::out|ios::app);
  if (out.is_open())
    out << "5\n";
  else
    cout << "unable to open res7 file";
  out.close();
     if (in.is_open()) {
    out.open("res7.txt", ios::out|ios::app);
    if (out.is_open())
      out << "6\n";
    else
      cout << "unable to open res7 file";
    out.close();
    char line[256];
    while (!in.getline(line, 256).eof()) {
      out.open("res7.txt", ios::out|ios::app);
      if (out.is_open())
    out << "7\n";
      else
    cout << "unable to open res7 file";
      out.close();
      char *input = strtok(line, " ");
      int i=0;
      while (input!=NULL) {
    out.open("res7.txt", ios::out|ios::app);
    if (out.is_open())
      out << "8\n";
    else
      cout << "unable to open res7 file";
    out.close();
    parameters[i] = atof(input);
    input = strtok(NULL, " ");
    i++;
      }
      int rnum = rand();
      location = rnum%10000;
      out.open("res7.txt", ios::out|ios::app);
      if (out.is_open())
    out << "9\n";
      else
    cout << "unable to open res7 file";
      out.close();
      Pop p(parameters[0], parameters[1], 0.2, 0.1, parameters[2], location);
      out.open("res7.txt", ios::out|ios::app);
      if (out.is_open())
    out << "10\n";
      else
    cout << "unable to open res7 file";
      out.close();
      double L = exp(-parameters[3]);
      double FF_mean = p.FF_steady(parameters[3], L, 0.0);
      out.open("res7.txt", ios::out|ios::app);
      if (out.is_open())
    out << "11\n";
      else
    cout << "unable to open res7 file";
      out.close();
      out.open("res7.txt", ios::out|ios::app);
      if (out.is_open()) {
    out << "number of chromosomes is " << p.all_population[0]->ga->chromosome << "  alpha is " << parameters[2] << "  cost is " << parameters[1];
    out << "  a is " << parameters[0] << "  u is " << parameters[3] << "  location is " << location << "  FF steady is " << FF_mean << '\n';
      }
      else
    cout << "unable to open res7 file FF";
      out.close();
      out.open("res7.txt", ios::out|ios::app);
      if (out.is_open())
    out << "12\n";
      else
    cout << "unable to open res7 file";
      out.close();
      if (FF_mean>0.1) {
    out.open("res7.txt", ios::out|ios::app);
    if (out.is_open())
      out << "13\n";
    else
      cout << "unable to open res7 file";
    out.close();
    p.insert_O(0.05);
    out.open("res7.txt", ios::out|ios::app);
    if (out.is_open())
      out << "14\n";
    else
      cout << "unable to open res7 file";
    out.close();
    double total_mean = p.steady(parameters[3], L, 0.0);
    double perc = p.perc_O();
    out.open("res7.txt", ios::out|ios::app);
    if (out.is_open())
      out << "total steady is " << total_mean << "   perc O is " << perc << '\n';
    else
      cout << "unable to open res7 file";
    out.close();
      }
    }
  }
  else
    cout << "Unable to open input7 file\n";
    in.close();
  return 0;
}

我在控制台上看不到任何输出。当我在另一台机器上运行代码时，我发现出现浮点异常。我想我可以找到它在哪里，但我不明白的是为什么我在 cygwin 的控制台上看不到任何输出或错误。谁能帮助我吗？

Answer 1

你确定代码可以编译吗？在倒数第三行

in.close();*/

，但是没有开始 /* 标记。我会确保您的代码确实正在编译并且生成了一个新的 .exe。您可能无法编译和运行没有任何 cout 的旧 .exe。

另外，你确定没有抛出异常吗？我无法完全测试代码，因为我缺少“Pop.h”的源代码，因此我无法完全看到编译时遇到的错误。您能否尝试在程序顶部进行初始cout，并可能向 Pop.h 提供源，以便我们可以对其进行更多测试。

Answer 2

首先，异常甚至可能在不提供信息的情况下终止程序。 Cygwin 是一种将 Windows 和 UNIX 结合起来的尝试，但事情并不总是完美。

其次，std::cout 是一个缓冲流。因此，每个运算符<<都会添加到缓冲区，直到缓冲区填满并自动输出，您可以使用cout.flush()显式刷新缓冲区，或者隐式刷新缓冲区，例如 std::endl 会导致。

因此，您需要使用调试器或其他系统来查找错误并修复它。您还需要在多个平台上进行测试，因为事情在不同的平台上表现得不同——包括不同的错误，甚至看起来工作正常。