I got the following code:
int days = round(durationTimeInterval / D_DAY);
int secondsLeft = durationTimeInterval - (days * D_DAY);
double hoursLeft = secondsLeft % D_HOUR;
double hours = round(hoursLeft);
if seconds left is 10710 then dividing by D_HOUR give me 2,975 I then want to round that up to 3 hours... Am not sure how to do this? Please advise.
You could use the round function or ceil function:
ROUND
CEIL
Related
I'm trying to do Integer division () by 0.25 but VB is telling me I tried to divide by zero, I also tried dividing by (1/4).
This is my snippet
AmountLeft = Remainder \ 0.25
lblQuartersAmount.Text = AmountLeft
You can't do integer division by a non-integer; just truncate and cast it afterwards.
AmountLeft = CInt(Math.Truncate(Remainder / 0.25))
And what's wrong with * 4? =)
Could anyone explain to me why this keeps returning 0 when it should return a value of 42? it works on paper so i know the math is right I'm just wondering as to why it isn't translating across?
int a = 60;
int b = 120;
int c = 85;
int progress;
progress = ((c-a)/(b-a))*100;
NSLog(#"Progess = %d %%",progress);
It's because your math is all using integers.
In particular, your inner expression is calculating 25 / 60, which in integer math is zero.
In effect you have over-parenthesised your expression, and the resulting order of evaluation is causing integer rounding problems.
It would have worked fine if you had just written the formula so:
progress = 100 * (c - a) / (b - a);
because the 100 * (c - a) would first evaluate to 2500, and would then be divided by 60 to give 41.
Alternative, if any one (or more) of your variables a, b, or c were a float (or cast thereto) the equation would also work.
That's because an expression in which either operand is a float will cause the other (integer) operand to be promoted to a float, too, at which point the result of the expression will also be a float.
c - a will give you 25
b - a will give you 60
Since a, b, and c are all integers, meaning they can't be decimals. Therefore, by doing (c-a)/(b-a), you will get 0, instead of 0.41666666 because in integer division, anything after the decimal point will get cut off, leaving the number before the decimal point.
To make it work the way you wanted it to, you should try casting (c-a) and (b-a) to either double or float:
progress = ((float)(c-a) / (float)(b-a)) * 100;
or
progress = ((double)(c-a) / (double)(b-a)) * 100;
a,b and c are ints. When you calculate ((c-a)/(b-a)), the result is also an int; the real value is a decimal (0.42), but an int can't take a decimal number, so it rounds to 0, which is multiplied by 100 to get 0.
Because (c - a) / (b - a) is computed using integer math.
To fix, cast to a float before dividing:
progress = (int)((((float)(c - a)) / ((float)(b - a))) * 100);
I got stuck with a problem that looked pretty easy but i cant make it work.
I'm making a simple download manager for OSX using objective C. As part of the app im trying to calculate the percentage of the current download. im trying to use this code but it wont work for me
long double precent = (bytesDownloaded/downloadSize) * 100;
NSLog(#"precnt %Lf",precent);
NSLog(#"Downloadedbyret: %lld", bytesDownloaded);
The bytesDownloaded and downloadSize are long long.
Can someone please advise,
thanks
To get the correct answer, you must cast the values to long double.
long double precent = ((long double)bytesDownloaded/(long double)downloadSize);
NSLog(#"precnt %Lf",precent);
NSLog(#"Downloadedbyret: %lld", bytesDownloaded);
Is the denominator an int, change it to a floating point? Try:
long double precent = (bytesDownloaded/(downloadSize * 1.0));
NSLog(#"precnt %Lf",precent);
NSLog(#"Downloadedbyret: %lld", bytesDownloaded);
To get % complete you need to multiply by 100.
long double precent = (bytesDownloaded/downloadSize) * 100.0;
if the values bytesDownloaded and downloadSize are int you will need to cast them to a floating point value.
Or if integers multiple the dividend by 100 first:
(bytesDownloaded * 100) / downloadSize;
I'm trying to calculate some numbers in an iPhone application.
int i = 12;
int o = (60 / (i * 50)) * 1000;
I would expect o to be 100 (that's milliseconds) in this example but it equals 0 as displayed by NSLog(#"%d", o).
This also equals 0.
int o = 60 / (i * 50) * 1000;
This equals 250,000, which is straight left-to-right math.
int o = 60 / i * 50 * 1000;
What's flying over my head here?
Thanks,
Nick
In Objective-C / performs integer division on integer arguments, so 4/5 is truncated to 0, 3/2 is truncated to 1, and so on. You probably want to cast some of your numbers to floating-point forms before performing division.
You're also running in to issues with precedence. In the expression
60 / (i * 50) * 1000
the term inside the parentheses is calculated first, so 60 is divided by 600 which produces the result 0. In
60 / i * 50 * 1000
the first operation is to divide 60 by 12 which gives the result 5 and then the multiplications are carried out.
An integer divided by an integer is an integer.
so 60/600 is not 0.1, it is 0.
Cast (or declare) some stuff as float instead.
It's doing integer math. 60 / (12 * 50) is 0.1, truncates to 0.
Should work if you force floating point and then cast back to an integer.
int o = (int)(60.0 / ((double) i / 50.0) * 1000.0;
Probably not really necessary to make everything a double.
Replace:
int o = (60 / (i * 50)) * 1000;
with:
int o = 1200/i;
By order of precedence, the operation:
60 / (12 * 50)
is performed before multiplying by 1000.
This value is less than 1 and is cast to an int, which truncates it to 0. And 0 times anything is 0.
Use a float or first multiply by 1000 to ensure you're not ending up with propagating a 0 in your calculations.
All the operations in your expression are performed in integer arithmetic, meaning that the fractional part of each intermediate result is truncated. This means that if you divide a smaller integer by a larger integer you will always get 0.
To get the result you want you must either make sure the operations are performed in a particular order, or you must use floats. For example the result of
int o = (60.0 / (i * 50.0)) * 1000.0;
should be o = 100.
I think you need to use float here instead of int. It will work the way you want! Will give you answer in decimals as well.
What is the syntax to round up a decimal leaving two digits after the decimal point?
Example: 2.566666 -> 2.57
If you want regular rounding, you can just use the Math.Round method. If you specifially want to round upwards, you use the Math.Ceiling method:
Dim d As Decimal = 2.566666
Dim r As Decimal = Math.Ceiling(d * 100D) / 100D
Here is how I do it:
Private Function RoundUp(value As Double, decimals As Integer) As Double
Return Math.Ceiling(value * (10 ^ decimals)) / (10 ^ decimals)
End Function
Math.Round is what you're looking for. If you're new to rounding in .NET - you should also look up the difference between AwayFromZero and ToEven rounding. The default of ToEven can sometime take people by surprise.
dim result = Math.Round(2.56666666, 2)
You can use System.Math, specifically Math.Round(), like this:
Math.Round(2.566666, 2)
Math.Round(), as suggested by others, is probably what you want. But the text of your question specifically asked how to "roundup"[sic]. If you always need to round up, regarless of actual value (ie: 2.561111 would still go to 2.57), you can do this:
Math.Ceiling(d * 100)/100D
The basic function for rounding up is Math.Ceiling(d), but the asker specifically wanted to round up after the second decimal place. This would be Math.Ceiling(d * 100) / 100. For example, it may multiply 46.5671 by 100 to get 4656.71, then rounds up to get 4657, then divides by 100 to shift the decimal back 2 places to get 46.57.
I used this way:
Math.Round(d + 0.49D, 2)
Math.Ceiling((14.512555) * 100) / 100
Dot net will give you 14.52. So, you can use above syntax to round the number up for 2 decimal numbers.
I do not understand why people are recommending the incorrect code below:
Dim r As Decimal = Math.Ceiling(d * 100D) / 100D
The correct code to round up should look like this:
Dim r As Double = Math.Ceiling(d)
Math.Ceiling works with data type Double (not Decimal).
The * 100D / 100D is incorrect will break your results for larger numbers.
Math.Ceiling documentation is found here: http://msdn.microsoft.com/en-us/library/zx4t0t48.aspx