Formatting a double to two decimal places

Question

I have been trying to make the answer this prints out to be to two decimal places  All the math involved has to stay at that format of two decimal places  I have tried a few things and I am not sure what to change to make this work     double pdt1   239 99  double pdt1Total  double pdt2   129 75  double pdt2Total  double pdt3   99 95  double pdt3Total  double pdt4   350 89  double pdt4Total  double wage   200  double percentage   9  double total  double answer  double i   100  double a  double b  double c  double d    Console Write  Enter number sold of product  1      a   Convert ToInt32 Console ReadLine      Console Write  Enter number sold of product  2      b   Convert ToInt32 Console ReadLine      Console Write  Enter number sold of product  3      c   Convert ToInt32 Console ReadLine      Console Write  Enter number sold of product  4      d   Convert ToInt32 Console ReadLine        pdt1Total   a   pdt1  pdt2Total   b   pdt2  pdt3Total   c   pdt3  pdt4Total   d   pdt4   total    pdt1Total   pdt2Total   pdt3Total   pdt4Total      string Format   0 0 00    total   string Format   0 0 00    answer    total   percentage   i    wage     Console WriteLine  Earnings this week    answer

User · Answer

Well  depending on your needs you can choose any of the following  Out put is written against each method  You can choose the one you need  This will round  decimal d   2 5789m  Console WriteLine d ToString              2 58   This will ensure that 2 decimal places are written   d   2 5m  Console WriteLine d ToString  F       2 50   if you want to write commas you can use this  d 23545789 5432m  Console WriteLine d ToString  n2       23 545 789 54   if you want to return the rounded of decimal value you can do this  d   2 578m  d   decimal Round d  2  MidpointRounding AwayFromZero     2 58

User · Answer

You can round a double to two decimal places like this   double c  c   Math Round c  2     But beware rounding will eventually bite you  so use it with caution   Instead use the decimal data type

User · Answer

The problem is that when you are doing additions and multiplications of numbers all with two decimal places  you expect there will be no rounding errors  but remember the internal representation of double is in base 2  not in base 10   So a number like 0 1 in base 10 may be in base 2   0 101010101010110011    with an infinite number of decimals  the value stored in the double will be a number N with      0 1-Math Pow 2 -64   lt  N  lt  0 1 Math Pow 2 -64     As a consequence an operation like 12 3    0 1 may be not the same exact 64 bits double value as 12 4  or 12 456   10 may be not the same as 124 56  because of rounding errors  For example if you store in a Database the result of 12 3  0 1 into a table column field of type double precision number and then SELECT WHERE xx 12 4 you may realize that you stored a number that is not exactly 12 4 and the Sql select will not return the record  So if you cannot use the decimal datatype  which has internal representation in base 10  and must use the  double  datatype  you have to do some normalization after each addition or multiplication    double freqMHz  freqkHz MulRound 0 001      freqkHz 0 001 double amountEuro  amountEuro AddRound delta      amountEuro delta       public static double AddRound this double d double val                return double Parse string Format   0 g14    d val              public static double MulRound this double d double val                return double Parse string Format   0 g14    d val

User · Answer

string Format will not change the original value  but it will return a formatted string  For example   Console WriteLine  Earnings this week   0 0 00    answer     Note  Console WriteLine allows inline string formatting  The above is equivalent to   Console WriteLine  Earnings this week      string Format   0 0 00    answer

User · Answer

double d    3 1493745      string s      d 0 00       or    d            Console WriteLine s      Displays 3 15

User · Answer

Since you are working in currency why not simply do this   Console Writeline  Earnings this week   0 c    answer     This will format answer as currency  so on my machine  UK  it will come out as   Earnings this week    209 00

User · Answer

I would recomment the Fixed-Point   F   format specifier  as mentioned by Ehsan   See the Standard Numeric Format Strings    With this option you can even have a configurable number of decimal places   public string ValueAsString double value  int decimalPlaces        return value ToString   F decimalPlaces

[c#] Formatting a double to two decimal places

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