How do I cast a double to an int?
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Hi, I have a program for work that uses a formula to calculate the refurb on a unit(parts replaced on cableboxes that were damaged) divided by total units(cableboxes that went through refurb, but did not have any parts replaced). I looked up casting online, and the format for it is intvaluetoconvert = Convert.toint32; I'm doing that , but still get the error Cannot implicitly convert type 'double to int. An explicit conversion exists(are you missing a cast?) What am I doing wrong? Can someone please help? Thank you. Justin Here's some of my code to look at? private int GetRefurbRate() { string sql = ""; double Refurb_Rate; int totalRefurb = 0; int totalUnits = 0; string error_msg = ""; sql = "SELECT COUNT(rp.repair_ord) " + "FROM " + schema + ".repair_part rp " + "WHERE rp.repair_ord = '" + repair_ord + "' "; while (true) { if (!myDb.RunSql(sql, true)) { error_msg = "DBError for getting Refurb Rate"; break; } if (myDb.dbRdr.HasRows) { if (myDb.dbRdr.Read()) { try //Try and Catch are here b/c I originally had everything ints, and and they just caught the 0 exception. { Refurb_Rate = Convert.ToInt32( totalRefurb / totalUnits * 100); //This is where I try to perform the cast. } catch (Exception e) { Console.WriteLine(e); } } //int Refurb_Rate = Convert.ToInt32(Refurb_Rate); } break; } myDb.dbRdr.Close(); if (error_msg != String.Empty) { MessageBox.Show(error_msg, "Get Refurb Rate", MessageBoxButtons.OK, MessageBoxIcon.Asterisk); } return Refurb_Rate; }
Justiin1265 wrote:
Refurb_Rate = Convert.ToInt32( totalRefurb / totalUnits * 100); //This is where I try to perform the cast.
this does not make sense, as all variables are declared integers, therefore the quotient will be integer too, and the Convert method does nothing for you. Furthermore, the result will not be what you expect: for totalRefurb=2, totalUnits=10, the formula looks like
2 / 10 * 100, unfortunately in an integer world2 / 10is zero. What you need to do is one of the following: - multiply first, i.e.100 * totalRefurb / totalUnits- use real numbers (i.e. data types such asfloatordouble), this will avoid overflow (when your integers near the max value), and perform rounding. :)Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum
Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.
modified on Monday, April 11, 2011 3:25 PM
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I have a program for work that uses a formula to calculate the refurb on a unit (parts replaced on cableboxes that were damaged) divided by total units(cableboxes that went through refurb, but did not have any parts replaced). I looked up casting online, and the format for it is
intvaluetoconvert = Convert.toint32;I'm doing that, but still get the error "Cannot implicitly convert type double to int. An explicit conversion exists (are you missing a cast?)" What am I doing wrong? Here's some of my code to look at:private int GetRefurbRate()
{
string sql = "";
double Refurb_Rate;
int totalRefurb = 0;
int totalUnits = 0;
string error_msg = "";sql = "SELECT COUNT(rp.repair\_ord) " + "FROM " + schema + ".repair\_part rp " + "WHERE rp.repair\_ord = '" + repair\_ord + "' "; while (true) { if (!myDb.RunSql(sql, true)) { error\_msg = "DBError for getting Refurb Rate"; break; } if (myDb.dbRdr.HasRows) { if (myDb.dbRdr.Read()) { try //Try and Catch are here b/c I originally had everything ints, and and they just caught the 0 exception. { Refurb\_Rate = Convert.ToInt32( totalRefurb / totalUnits \* 100); //This is where I try to perform the cast. } catch (Exception e) { Console.WriteLine(e); } } //int Refurb\_Rate = Convert.ToInt32(Refurb\_Rate); } break; } myDb.dbRdr.Close(); if (error\_msg != String.Empty) { MessageBox.Show(error\_msg, "Get Refurb Rate", MessageBoxButtons.OK, MessageBoxIcon.Asterisk); } return Refurb\_Rate;}
This is not the age of reason, this is the age of flummery, and the day of the devious approach. Reason’s gone into the backrooms where it works to devise means by which people can be induced to emote in the desired direction.
Congrats on the PRE tags, however the percentage formula isn't quite OK... see my other msg. :)
Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum
Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.
-
Justiin1265 wrote:
Refurb_Rate = Convert.ToInt32( totalRefurb / totalUnits * 100); //This is where I try to perform the cast.
this does not make sense, as all variables are declared integers, therefore the quotient will be integer too, and the Convert method does nothing for you. Furthermore, the result will not be what you expect: for totalRefurb=2, totalUnits=10, the formula looks like
2 / 10 * 100, unfortunately in an integer world2 / 10is zero. What you need to do is one of the following: - multiply first, i.e.100 * totalRefurb / totalUnits- use real numbers (i.e. data types such asfloatordouble), this will avoid overflow (when your integers near the max value), and perform rounding. :)Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum
Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.
modified on Monday, April 11, 2011 3:25 PM
I deleted my crap responses. Yours is more... what is the word? Oh yes, "correct". :)
This is not the age of reason, this is the age of flummery, and the day of the devious approach. Reason’s gone into the backrooms where it works to devise means by which people can be induced to emote in the desired direction.
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I deleted my crap responses. Yours is more... what is the word? Oh yes, "correct". :)
This is not the age of reason, this is the age of flummery, and the day of the devious approach. Reason’s gone into the backrooms where it works to devise means by which people can be induced to emote in the desired direction.
"More correct"? A purist might object, some characteristics really are binary. :-D I'm not saying it is correct now (I still don't get what the OP is after), I do think one more problem has been addressed though.
Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum
Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.
-
It shows the error at Refurb_Rate = Convert.ToInt32( totalRefurb / totalUnits * 100); I'm trying to convert the doulbe back to an integer, so I figured use the conversion syntax to return to an integer.
Refurb_Rate is a double, so when you return it later on, it is still holding a double (even though that double may happen to be integral). Since your function is of return type "int", you need to ensure you return data type "int". Luc addresses some other issues with your code below.
This is not the age of reason, this is the age of flummery, and the day of the devious approach. Reason’s gone into the backrooms where it works to devise means by which people can be induced to emote in the desired direction.
-
Justiin1265 wrote:
Refurb_Rate = Convert.ToInt32( totalRefurb / totalUnits * 100); //This is where I try to perform the cast.
this does not make sense, as all variables are declared integers, therefore the quotient will be integer too, and the Convert method does nothing for you. Furthermore, the result will not be what you expect: for totalRefurb=2, totalUnits=10, the formula looks like
2 / 10 * 100, unfortunately in an integer world2 / 10is zero. What you need to do is one of the following: - multiply first, i.e.100 * totalRefurb / totalUnits- use real numbers (i.e. data types such asfloatordouble), this will avoid overflow (when your integers near the max value), and perform rounding. :)Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum
Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.
modified on Monday, April 11, 2011 3:25 PM
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Hey now, neither float nor double can represent all reals. They can only represent (some) rationals (and -0, NaN, +/-Infinity).
David1987 wrote:
neither float nor double can represent all reals
I agree (and I'll add nothing can represent just any real number's value); I also didn't say such thing. :)
Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum
Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.
-
David1987 wrote:
neither float nor double can represent all reals
I agree (and I'll add nothing can represent just any real number's value); I also didn't say such thing. :)
Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum
Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.
No.. but you said "real numbers" and "float" in the same sentence, it might give people the wrong idea. I've known plenty of people who were told by a teacher that doubles are "real numbers" (which is almost true if it's put like that - except for NaN and infinities and -0) and they were all confused and surprised when their calculations gave the "wrong" results because they expected all reals to be representable by doubles.
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No.. but you said "real numbers" and "float" in the same sentence, it might give people the wrong idea. I've known plenty of people who were told by a teacher that doubles are "real numbers" (which is almost true if it's put like that - except for NaN and infinities and -0) and they were all confused and surprised when their calculations gave the "wrong" results because they expected all reals to be representable by doubles.
Yes, it would have been better to put
floatandrealin code-style. I'll fix that. I use "real numbers" for non-integer numbers (or better yet, numbers not restricted to integer values), and not for "exact numbers". Most programmers do it that way; it may originate in the old days of Fortran, where they had type REAL (there wasn't a FLOAT time then). And calculus (as well as programming) courses should teach people about number representations, errors, accumulation and propagation of errors, etc. Most programmers understand the square root of two isn't exact inside a computer, yet many have a hard time understanding why one third times three isn't always one. :)Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum
Please use <PRE> tags for code snippets, they preserve indentation, improve readability, and make me actually look at the code.
-
Hi, I have a program for work that uses a formula to calculate the refurb on a unit(parts replaced on cableboxes that were damaged) divided by total units(cableboxes that went through refurb, but did not have any parts replaced). I looked up casting online, and the format for it is intvaluetoconvert = Convert.toint32; I'm doing that , but still get the error Cannot implicitly convert type 'double to int. An explicit conversion exists(are you missing a cast?) What am I doing wrong? Can someone please help? Thank you. Justin Here's some of my code to look at? private int GetRefurbRate() { string sql = ""; double Refurb_Rate; int totalRefurb = 0; int totalUnits = 0; string error_msg = ""; sql = "SELECT COUNT(rp.repair_ord) " + "FROM " + schema + ".repair_part rp " + "WHERE rp.repair_ord = '" + repair_ord + "' "; while (true) { if (!myDb.RunSql(sql, true)) { error_msg = "DBError for getting Refurb Rate"; break; } if (myDb.dbRdr.HasRows) { if (myDb.dbRdr.Read()) { try //Try and Catch are here b/c I originally had everything ints, and and they just caught the 0 exception. { Refurb_Rate = Convert.ToInt32( totalRefurb / totalUnits * 100); //This is where I try to perform the cast. } catch (Exception e) { Console.WriteLine(e); } } //int Refurb_Rate = Convert.ToInt32(Refurb_Rate); } break; } myDb.dbRdr.Close(); if (error_msg != String.Empty) { MessageBox.Show(error_msg, "Get Refurb Rate", MessageBoxButtons.OK, MessageBoxIcon.Asterisk); } return Refurb_Rate; }
Give this a try this should fix your problem;
return (int)Refurb_Rate;