断言失败 [英] assert failure

问题描述

我有以下代码，但我不明白为什么断言失败？

我打印出我的价值我检查，它有正确的价值，但

断言仍然失败。


这是代码：

// bd.areaPerCent的类型为''浮动''

cout<< a.areaPerCent<< endl;

断言（a.areaPerCent == 0.00137389）;


这是节目的输出：

0.00137389

snapshot：../ TestBlockData.cpp：31：void TestBlockData :: test1（）：

断言`a.areaPerCent == 0.00137389''失败。


为什么会失败？

解决方案

ke ********* @ gmail.com 写道：

我有以下代码，但我不明白为什么断言失败？
我打印出我检查的值，它有正确的值，但
断言仍然失败。

以下是代码：
// bd.areaPerCent类型为''float''

cout<< a.areaPerCent<<断言;
断言（a.areaPerCent == 0.00137389）;

以下是该程序的输出：
0.00137389
snapshot：../ TestBlockData.cpp： 31：void TestBlockData :: test1（）：
断言`a.areaPerCent == 0.00137389''失败。

为什么失败？

==比较是以二进制浮点执行的，而不是您输出的ASCII

表示。 ASCII和二进制之间的翻译

float通常是不准确的。这是一个基本的编程错误使用==到

比较花车。


-

Scott McPhillips [VC ++ MVP]

谢谢。你能否告诉我如何比较浮动？

ke ********* @ gmail.com 写道：

我有下列内容代码，但我不明白为什么断言失败？
我打印出我检查的值，它有正确的值，但
断言仍然失败。
// bd.areaPerCent类型''浮动''

cout<< a.areaPerCent<<断言;
断言（a.areaPerCent == 0.00137389）;

以下是该程序的输出：
0.00137389
snapshot：../ TestBlockData.cpp： 31：void TestBlockData :: test1（）：
断言`a.areaPerCent == 0.00137389''失败。

为什么失败？

http://www.parashift.com/ c ++ - faq-lit ... html＃faq-29.17


Best


Kai-Uwe Bux

Hi,

I have the follwing code, but I can''t understand why the assert fail?
I print out the value that I am check, it has the right value, but the
assert still fail.

Here is the code:
// bd.areaPerCent is of type ''float''

cout << a.areaPerCent << endl;
assert (a.areaPerCent == 0.00137389);

Here is the output of the program:
0.00137389
snapshot: ../TestBlockData.cpp:31: void TestBlockData::test1():
Assertion `a.areaPerCent == 0.00137389'' failed.

why it fails?

解决方案

ke*********@gmail.com wrote:

Hi,

I have the follwing code, but I can''t understand why the assert fail?
I print out the value that I am check, it has the right value, but the
assert still fail.

Here is the code:
// bd.areaPerCent is of type ''float''

cout << a.areaPerCent << endl;
assert (a.areaPerCent == 0.00137389);

Here is the output of the program:
0.00137389
snapshot: ../TestBlockData.cpp:31: void TestBlockData::test1():
Assertion `a.areaPerCent == 0.00137389'' failed.

why it fails?

The == comparison is performed in binary floating point, not the ASCII
representation that you output. Translations between ASCII and binary
float are often inexact. It is a basic programming error to use == to
compare floats.

--
Scott McPhillips [VC++ MVP]

Thanks. Can you please tell me how should I compare float instead?

ke*********@gmail.com wrote:

Hi,

I have the follwing code, but I can''t understand why the assert fail?
I print out the value that I am check, it has the right value, but the
assert still fail.

Here is the code:
// bd.areaPerCent is of type ''float''

cout << a.areaPerCent << endl;
assert (a.areaPerCent == 0.00137389);

Here is the output of the program:
0.00137389
snapshot: ../TestBlockData.cpp:31: void TestBlockData::test1():
Assertion `a.areaPerCent == 0.00137389'' failed.

why it fails?

http://www.parashift.com/c++-faq-lit...html#faq-29.17

Best

Kai-Uwe Bux

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