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Schizoid Man
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 Posted: Mon Aug 28, 2006 9:10 am Post subject: Strange behavior of fmod() |
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I have the following code snippet where I am validating time in minutes
and hours entered in as a double variable.
If I enter the value 10.59, the value printed out is 10:58. For this
input, the correct value is being passed to 'temp', so I just can't
figure out why fmod() is misbehaving.
Any ideas?
double InputTime, temp;
int Hours, Minutes;
cout << "Enter the start time: ";
cin >> InputTime;
Hours = static_cast<int>(InputTime);
temp = InputTime - Hours;
temp = temp * 100.0;
Minutes = fmod(temp, 100);
cout << "Time is " << Hours << ":" << Minutes; |
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peter koch
Guest
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| Posted: Mon Aug 28, 2006 9:10 am Post subject: Re: Strange behavior of fmod() |
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Schizoid Man wrote:
| Quote: | I have the following code snippet where I am validating time in minutes
and hours entered in as a double variable.
If I enter the value 10.59, the value printed out is 10:58. For this
input, the correct value is being passed to 'temp', so I just can't
figure out why fmod() is misbehaving.
Any ideas?
double InputTime, temp;
int Hours, Minutes;
cout << "Enter the start time: ";
cin >> InputTime;
Hours = static_cast<int>(InputTime);
temp = InputTime - Hours;
temp = temp * 100.0;
Minutes = fmod(temp, 100);
cout << "Time is " << Hours << ":" << Minutes;
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You need to look-up floating-point precision.
/Peter |
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Schizoid Man
Guest
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| Posted: Mon Aug 28, 2006 9:10 am Post subject: Re: Strange behavior of fmod() |
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Schizoid Man wrote:
| Quote: | If I enter the value 10.59, the value printed out is 10:58. For this
input, the correct value is being passed to 'temp', so I just can't
figure out why fmod() is misbehaving.
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Taking a closer look, it seems that this code works properly till 10.50.
For 10.50 the time is 10:50, so far so good.
For 10.51 the time is 10:50, which is very odd indeed.
I really would appreciate some help. |
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Schizoid Man
Guest
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| Posted: Mon Aug 28, 2006 9:10 am Post subject: Re: Strange behavior of fmod() |
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Schizoid Man wrote:
| Quote: | Taking a closer look, it seems that this code works properly till 10.50.
For 10.50 the time is 10:50, so far so good.
For 10.51 the time is 10:50, which is very odd indeed.
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On further analysis, it seems that this problem only occurs if the input
is between 10.51 and 10.71.
This is very strange indeed. I really would appreciate any help at all.
Thanks. |
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