Drip Supplements-Custom Format control String.Format behavior

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String.Format the signature of an overloaded method is as follows

1  Public Static string format (2    IFormatProvider provider,3     string  format,  4     params  object[] args5 )

You can control specific behavior during String.Format execution by customizing the IFormatProvider interface.

The process is as follows

1, custom class implementation  iformatprovider interface (object GetFormat method)

1  Public Object GetFormat (Type formattype) 2 {3     if typeof (ICustomFormatter)) 4         return  This ; 5     Else 6         return NULL ; 7 }

2, implement ICustomFormatter excuse (string Format method)

Excerpt from MSDN. The function is a string output that controls the Int64 type.

1  Public stringFormat (stringFmtObjectArg, IFormatProvider formatprovider)2 {3     //provide default formatting if Arg is a Int64.4     if(Arg. GetType ()! =typeof(Int64))5         Try6         {7             returnhandleotherformats (FMT, arg);8         }9         Catch(FormatException e)Ten         { One             Throw NewFormatException (String.Format ("The format of ' {0} ' is invalid.", FMT), e); A         } -  -     //provide default formatting for unsupported format strings. the     stringUFMT =FMT. ToUpper (CultureInfo.InvariantCulture); -     if(! (Ufmt = ="H"|| UFMT = ="I")) -         Try -         { +             returnhandleotherformats (FMT, arg); -         } +         Catch(FormatException e) A         { at             Throw NewFormatException (String.Format ("The format of ' {0} ' is invalid.", FMT), e); -         } -  -     //Convert argument to a string. -     stringresult =Arg. ToString (); -  in     //If account number was less than characters, pad with leading zeroes. -     if(result.) Length <acct_length) toresult = result. PadLeft (Acct_length,'0'); +     //If account number was more than characters, truncate to characters. -     if(result.) Length >acct_length) theresult = result. Substring (0, acct_length); *  $     if(Ufmt = ="I")//integer-only format. Panax Notoginseng         returnresult; -     //Add hyphens for H format specifier. the     Else                                          //hyphenated format. +         returnResult. Substring (0,5) +"-"+ result. Substring (5,3) +"-"+ result. Substring (8); A}

Using the well-implemented Format class

1 LongAcctnumber;2 Doublebalance;3 DaysOfWeek wday;4 stringoutput;5 6Acctnumber =104254567890;7Balance =16.34;8Wday =Daysofweek.monday;9 TenOutput = String.Format ((NewAcctNumberFormat (), One                        "On {2}, the balance of account {0:h} is {1:C2}.", A Acctnumber, balance, wday); -Console.WriteLine (output);

Execution results are as follows

Resources

Culture invariant Decimal.tryparse () http://stackoverflow.com/questions/23131414/culture-invariant-decimal-tryparse

What does IFormatProvider do? Http://stackoverflow.com/questions/506676/what-does-iformatprovider-do

IFormatProvider Interface https://msdn.microsoft.com/en-us/library/system.iformatprovider.aspx

Drip Supplements-Custom Format control String.Format behavior