开启/关闭浮点数异常报错

Posted 2020-10-18 CodeSkill

tags:

篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了开启/关闭浮点数异常报错相关的知识，希望对你有一定的参考价值。

ZC: Delphi7 中的报错信息为（主要信息）："Invalid floating point operation"

1、http://bbs.csdn.net/topics/391070674　　（LongWord($133f)这句是什么意思-CSDN论坛.html）

　　2楼：

这个应该用_control87或者_controlfp
#include <float.h>
_control87(0x133f, 0xffff);
至于LongWord($133f)这是没有什么意义的，LongWord($133f)=$0000133f，32位无符号整数，仅此而已。

　　4楼：

// Default value (with exceptions) is 0x1372.这个注释是错的，默认值是0x1332。
Set8087CW是Delphi RTL函数，C++中最好还是用_control87或者_controlfp。

2、官方资料：

　　2.1、Set8087CW (C++) - RAD Studio Code Examples.html　　（http://docwiki.embarcadero.com/CodeExamples/XE8/en/Set8087CW_%28C%2B%2B%29）

Description

This example accesses the Floating Point Unit (FPU) control register. Try turning floating point exceptions off and on and dividing a number by zero to test it.

Code

Word Saved8087CW;
 
void __fastcall TForm1::Button1Click(TObject *Sender)
{
  Edit3->Text = FloatToStr(StrToFloat(Edit1->Text) / StrToFloat(Edit2->Text));
}
 
void __fastcall TForm1::RadioGroup1Click(TObject *Sender)
{
  if (RadioGroup1->Items->Strings[RadioGroup1->ItemIndex] == "FPU Exceptions")
	System::Set8087CW(Saved8087CW);
  if (RadioGroup1->Items->Strings[RadioGroup1->ItemIndex] == "No FPU Exceptions")
	System::Set8087CW(0x133f); // Disable all fpu exceptions.
}
 
__fastcall TForm1::TForm1(TComponent* Owner)
  : TForm(Owner)
{
  RadioGroup1->Items->Add("No FPU Exceptions");
  RadioGroup1->Items->Add("FPU Exceptions");
  RadioGroup1->ItemIndex = 2;
  Saved8087CW = Default8087CW;  // Save this, because Set8087CW changes it.
}
 
void __fastcall TForm1::FormDestroy(TObject *Sender)
{
  System::Set8087CW(Saved8087CW); // Default value (with exceptions) is 0x1372.
}

Uses

System.Set8087CW ( fr | de | ja )
System.Default8087CW ( fr | de | ja )

开启/关闭浮点数异常报错

Description

Code

Uses

See Also