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当任何数学运算产生“nan”时,如何强制C编译器抛出异常?

math exception c#

Trap · 技术社区 · 15 年前

我最近编写的程序中的一些数学函数返回了不可接受的值,比如NaN(可能是因为没有检查某些函数的输入参数)。问题是很难追踪哪些函数传递了错误的值。这会导致错误在整个代码中传播,并使程序在几分钟或几小时后崩溃(如果有的话)。

我不知道是否有一种方法来捕捉这些错误的操作的时刻,一个NaN值的结果,任何操作(几乎相同的'除法零异常'抛出一些C/C++编译器,如果我记得)。

事先谢谢。

P.D:如果需要,请随时重新标记我的问题。

6 回复 | 直到 11 年前

ChrisF 15 年前

if (double.IsNaN(result))
{
    throw new ArithmeticException();
}

Michael Brandl 11 年前

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Runtime.InteropServices;

namespace ConsoleApplication2
{
  class Program
  {
    [System.Runtime.InteropServices.DllImport("msvcrt.dll")]
    public static extern uint _control87(uint a, uint b);

    [System.Runtime.InteropServices.DllImport("msvcrt.dll")]
    public static extern uint _clearfp();

    static void Main(string[] args)
    {
      float zero = 0.0f - args.Length; // Want 0.0f. Fool compiler...
      System.Console.WriteLine("zero = " + zero.ToString());

      // A NaN which does not throw exception
      float firstNaN = zero / 0.0f;
      System.Console.WriteLine("firstNaN= " + firstNaN.ToString());

      // Now turn on floating-point exceptions
      uint empty = 0;
      uint cw = _control87(empty, empty); // Debugger halts on this one and complains about false signature, but continue works.
      System.Console.WriteLine(cw.ToString());
      uint MCW_EM = 0x0008001f; // From float.h
      uint _EM_INVALID = 0x00000010; // From float.h (invalid corresponds to NaN
      // See http://www.fortran-2000.com/ArnaudRecipes/CompilerTricks.html#x86_FP

      cw &= ~(_EM_INVALID);
      _clearfp(); // Clear floating point error word.
      _control87(cw, MCW_EM); // Debugger halts on this one and complains about false signature, but continue works.      
      System.Console.WriteLine(cw.ToString());

      // A NaN which does throw exception
      float secondNaN = 0;
      try
      {
        // Put as much code here as you like.
        // Enable "break when an exception is thrown" in the debugger
        // for system exceptions to get to the line where it is thrown 
        // before catching it below.
        secondNaN = zero / 0.0f;
      }
      catch (System.Exception ex)
      {
        _clearfp(); // Clear floating point error word.
      }      

      System.Console.WriteLine("secondNaN= " + secondNaN.ToString());
    }
  }
}

Alexander Torstling 15 年前

_controlfp_s

unsigned int _oldState;
errno_t err = _controlfp_s(&oldState, 0, MCW_EM);
assert(!err);

errno_t err = _controlfp_s(0, _oldState, MCW_EM);
assert(!err);

Steve 15 年前

int NaN checked

#if DEBUG

user 11 年前

TIntegerType SafeInt

Community CDub 7 年前

Conditional Debug