What does IFormatProvider do

Question

I was playing around with the Datetime ParseExact method  and it wants an IFormatProvider     It works inputting null  but what exactly does it do

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The DateTimeFormatInfo class implements this interface  so it allows you to control the formatting of your DateTime strings

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Check http   msdn microsoft com en-us library system iformatprovider aspx for the API

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Check http   msdn microsoft com en-us library system iformatprovider aspx for the API

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IFormatProvider provides culture info to the method in question  DateTimeFormatInfo implements IFormatProvider  and allows you to specify the format you want your date time to be displayed in  Examples can be found on the relevant MSDN pages

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The IFormatProvider interface is normally implemented for you by a CultureInfo class  e g    CultureInfo CurrentCulture CultureInfo CurrentUICulture CultureInfo InvariantCulture CultureInfo CreateSpecificCulture  quot de-CA quot     German  Canada   The interface is a gateway for a function to get a set of culture-specific data from a culture  The two commonly available culture objects that an IFormatProvider can be queried for are   DateTimeFormatInfo NumberFormatInfo  The way it would normally work is you ask the IFormatProvider to give you a DateTimeFormatInfo object  DateTimeFormatInfo format  format    DateTimeFormatInfo provider GetFormat typeof DateTimeFormatInfo    if  format    null     DoStuffWithDatesOrTimes format    There s also inside knowledge that any IFormatProvider interface is likely being implemented by a class that descends from CultureInfo  or descends from DateTimeFormatInfo  so you could cast the interface directly  CultureInfo info   provider as CultureInfo  if  info    null     format   info DateTimeInfo  else      DateTimeFormatInfo dtfi   provider as DateTimeFormatInfo     if  dtfi    null         format   dtfi     else        format    DateTimeFormatInfo provider GetFormat typeof DateTimeFormatInfo       if  format    null     DoStuffWithDatesOrTimes format    But don t do that All that hard work has already been written for you  To get a DateTimeFormatInfo from an IFormatProvider  DateTimeFormatInfo format   DateTimeFormatInfo GetInstance provider    To get a NumberFormatInfo from an IFormatProvider  NumberFormatInfo format   NumberFormatInfo GetInstance provider    The value of IFormatProvider is that you create your own culture objects  As long as they implement IFormatProvider  and return objects they re asked for  you can bypass the built-in cultures  You can also use IFormatProvider for a way of passing arbitrary culture objects - through the IFormatProvider  E g  the name of god in different cultures  god God Jehova Yahwe                     This lets your custom LordsNameFormatInfo class ride along inside an IFormatProvider  and you can preserve the idiom  In reality you will never need to call GetFormat method of IFormatProvider yourself  Whenever you need an IFormatProvider you can pass a CultureInfo object  DateTime Now ToString CultureInfo CurrentCulture    endTime ToString CultureInfo InvariantCulture    transactionID toString CultureInfo CreateSpecificCulture  quot qps-ploc quot       Note  Any code is released into the public domain  No attribution required

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Check http   msdn microsoft com en-us library system iformatprovider aspx for the API

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In adition to Ian Boyd s answer   Also CultureInfo implements this interface and can be used in your case  So you could parse a French date string for example  you could use  var ci   new CultureInfo  fr-FR    DateTime dt   DateTime ParseExact yourDateInputString  yourFormatString  ci

User · Answer

IFormatProvider provides culture info to the method in question  DateTimeFormatInfo implements IFormatProvider  and allows you to specify the format you want your date time to be displayed in  Examples can be found on the relevant MSDN pages

User · Answer

IFormatProvider provides culture info to the method in question  DateTimeFormatInfo implements IFormatProvider  and allows you to specify the format you want your date time to be displayed in  Examples can be found on the relevant MSDN pages

User · Answer

You can see here http   msdn microsoft com en-us library system iformatprovider aspx  See the remarks and example section there

User · Answer

You can see here http   msdn microsoft com en-us library system iformatprovider aspx  See the remarks and example section there

User · Answer

The DateTimeFormatInfo class implements this interface  so it allows you to control the formatting of your DateTime strings

User · Answer

Check http   msdn microsoft com en-us library system iformatprovider aspx for the API

User · Answer

By MSDN  The  NET Framework includes the following three predefined IFormatProvider implementations to provide culture-specific information that is used in formatting or parsing numeric and date and time values    The NumberFormatInfo class  which provides information that is used to format numbers  such as the currency  thousands separator  and decimal separator symbols for a particular culture  For information about the predefined format strings recognized by a NumberFormatInfo object and used in numeric formatting operations  see Standard Numeric Format Strings and Custom Numeric Format Strings  The DateTimeFormatInfo class  which provides information that is used to format dates and times  such as the date and time separator symbols for a particular culture or the order and format of a date s year  month  and day components  For information about the predefined format strings recognized by a DateTimeFormatInfo object and used in numeric formatting operations  see Standard Date and Time Format Strings and Custom Date and Time Format Strings  The CultureInfo class  which represents a particular culture  Its GetFormat method returns a culture-specific NumberFormatInfo or DateTimeFormatInfo object  depending on whether the CultureInfo object is used in a formatting or parsing operation that involves numbers or dates and times    The  NET Framework also supports custom formatting  This typically involves the creation of a formatting class that implements both IFormatProvider and ICustomFormatter  An instance of this class is then passed as a parameter to a method that performs a custom formatting operation  such as String Format IFormatProvider  String  Object

User · Answer

The DateTimeFormatInfo class implements this interface  so it allows you to control the formatting of your DateTime strings

User · Answer

In adition to Ian Boyd s answer   Also CultureInfo implements this interface and can be used in your case  So you could parse a French date string for example  you could use  var ci   new CultureInfo  fr-FR    DateTime dt   DateTime ParseExact yourDateInputString  yourFormatString  ci

User · Answer

IFormatProvider provides culture info to the method in question  DateTimeFormatInfo implements IFormatProvider  and allows you to specify the format you want your date time to be displayed in  Examples can be found on the relevant MSDN pages

User · Answer

In adition to Ian Boyd s answer   Also CultureInfo implements this interface and can be used in your case  So you could parse a French date string for example  you could use  var ci   new CultureInfo  fr-FR    DateTime dt   DateTime ParseExact yourDateInputString  yourFormatString  ci

User · Answer

The IFormatProvider interface is normally implemented for you by a CultureInfo class  e g    CultureInfo CurrentCulture CultureInfo CurrentUICulture CultureInfo InvariantCulture CultureInfo CreateSpecificCulture  quot de-CA quot     German  Canada   The interface is a gateway for a function to get a set of culture-specific data from a culture  The two commonly available culture objects that an IFormatProvider can be queried for are   DateTimeFormatInfo NumberFormatInfo  The way it would normally work is you ask the IFormatProvider to give you a DateTimeFormatInfo object  DateTimeFormatInfo format  format    DateTimeFormatInfo provider GetFormat typeof DateTimeFormatInfo    if  format    null     DoStuffWithDatesOrTimes format    There s also inside knowledge that any IFormatProvider interface is likely being implemented by a class that descends from CultureInfo  or descends from DateTimeFormatInfo  so you could cast the interface directly  CultureInfo info   provider as CultureInfo  if  info    null     format   info DateTimeInfo  else      DateTimeFormatInfo dtfi   provider as DateTimeFormatInfo     if  dtfi    null         format   dtfi     else        format    DateTimeFormatInfo provider GetFormat typeof DateTimeFormatInfo       if  format    null     DoStuffWithDatesOrTimes format    But don t do that All that hard work has already been written for you  To get a DateTimeFormatInfo from an IFormatProvider  DateTimeFormatInfo format   DateTimeFormatInfo GetInstance provider    To get a NumberFormatInfo from an IFormatProvider  NumberFormatInfo format   NumberFormatInfo GetInstance provider    The value of IFormatProvider is that you create your own culture objects  As long as they implement IFormatProvider  and return objects they re asked for  you can bypass the built-in cultures  You can also use IFormatProvider for a way of passing arbitrary culture objects - through the IFormatProvider  E g  the name of god in different cultures  god God Jehova Yahwe                     This lets your custom LordsNameFormatInfo class ride along inside an IFormatProvider  and you can preserve the idiom  In reality you will never need to call GetFormat method of IFormatProvider yourself  Whenever you need an IFormatProvider you can pass a CultureInfo object  DateTime Now ToString CultureInfo CurrentCulture    endTime ToString CultureInfo InvariantCulture    transactionID toString CultureInfo CreateSpecificCulture  quot qps-ploc quot       Note  Any code is released into the public domain  No attribution required

User · Answer

The DateTimeFormatInfo class implements this interface  so it allows you to control the formatting of your DateTime strings

User · Answer

In adition to Ian Boyd s answer   Also CultureInfo implements this interface and can be used in your case  So you could parse a French date string for example  you could use  var ci   new CultureInfo  fr-FR    DateTime dt   DateTime ParseExact yourDateInputString  yourFormatString  ci

User · Answer

Passing null as the IFormatProvider is not the correct way to do this  If the user has a custom date time format on their PC you ll have issues in parsing and converting to string  I ve just fixed a bug where somebody had passed null as the IFormatProvider when converting to string   Instead you should be using CultureInfo InvariantCulture  Wrong   string output   theDate ToString  dd MM yy HH mm ss fff   null     Correct   string output   theDate ToString  dd MM yy HH mm ss fff   CultureInfo InvariantCulture

User · Answer

You can see here http   msdn microsoft com en-us library system iformatprovider aspx  See the remarks and example section there

User · Answer

By MSDN  The  NET Framework includes the following three predefined IFormatProvider implementations to provide culture-specific information that is used in formatting or parsing numeric and date and time values    The NumberFormatInfo class  which provides information that is used to format numbers  such as the currency  thousands separator  and decimal separator symbols for a particular culture  For information about the predefined format strings recognized by a NumberFormatInfo object and used in numeric formatting operations  see Standard Numeric Format Strings and Custom Numeric Format Strings  The DateTimeFormatInfo class  which provides information that is used to format dates and times  such as the date and time separator symbols for a particular culture or the order and format of a date s year  month  and day components  For information about the predefined format strings recognized by a DateTimeFormatInfo object and used in numeric formatting operations  see Standard Date and Time Format Strings and Custom Date and Time Format Strings  The CultureInfo class  which represents a particular culture  Its GetFormat method returns a culture-specific NumberFormatInfo or DateTimeFormatInfo object  depending on whether the CultureInfo object is used in a formatting or parsing operation that involves numbers or dates and times    The  NET Framework also supports custom formatting  This typically involves the creation of a formatting class that implements both IFormatProvider and ICustomFormatter  An instance of this class is then passed as a parameter to a method that performs a custom formatting operation  such as String Format IFormatProvider  String  Object

User · Answer

Passing null as the IFormatProvider is not the correct way to do this  If the user has a custom date time format on their PC you ll have issues in parsing and converting to string  I ve just fixed a bug where somebody had passed null as the IFormatProvider when converting to string   Instead you should be using CultureInfo InvariantCulture  Wrong   string output   theDate ToString  dd MM yy HH mm ss fff   null     Correct   string output   theDate ToString  dd MM yy HH mm ss fff   CultureInfo InvariantCulture

User · Answer

You can see here http   msdn microsoft com en-us library system iformatprovider aspx  See the remarks and example section there

[c#] What does IFormatProvider do?

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