Features of Transformation of Real Numbers and Dates into Strings and Back

Article number: KB000012

General Information

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Description

There are two methods of converting real numbers or dates into strings and back: using the ToString and Parse methods and methods of the CultureInfo static class.

The ToString and Parse methods are used to convert numbers or dates without taking into account regional settings and operating system. The ToString method returns a string that can be saved to a database. On another computer (with another operating system or regional settings) this database string can be converted to original number by calling the Parse method. These data is correct.

Methods of the CultureInfo static class are used to convert numbers and dates taking into account regional settings and operating system of a user, that is, to display data correctly.

ToString and Parse Methods

All transformations are executed without taking into account regional settings and operating system.

Method	Syntax	Description
ToString	ToString;	Converts a value to a string.
Parse	Parse(Value: String);	Returns a value converted from a string to a system type.

Methods of the CultureInfo Class Used to Convert Real Numbers and Dates

All transformations are executed taking into account regional settings and operating system.

Method	Syntax	Description
FormatDouble	FormatDouble(Value: Double): String;	Converts a real number into a string.
FormatDoublePrec	FormatDoublePrec (Value:Double; Precision: Integer): String;	Converts a real number into a string with specified accuracy.
ParseDouble	ParseDouble(Value: String): Double;	Returns a real number converted from a string.
TryParseDouble	TryParseDouble (Value: String; Result: Double): Boolean;	Returns True if transformation of a real number from a string is successful.
FormatDateTime	FormatDateTime(Value: DateTime): String;	Converts a date (with time) to a string.
FormatDate	FormatDate(Value: DateTime): String;	Converts a date (without time) to a string.
FormatDateEx	FormatDateEx (Value: DateTime; Format: String): String;	Converts a date to a string considering the specified format.
FormatShortDate	FormatShortDate(Value: DateTime): String;	Converts a date to a string (short format, for example, 06.06.2006).
FormatLongDate	FormatLongDate(Value: DateTime): String;	Converts a date to a string (full format, for example, 6 June 2006).
ParseDateTime	ParseDateTime(Value: String): DateTime;	Returns a date (with time) converted from a string.
ParseDate	ParseDate(Value: String): DateTime;	Returns a date (without time) converted from a string.

Example

Sub UserProc;
Var
    CF: ICultureInfo;
    s: String;
Begin
    CF := CultureInfo.Current;
    s := CF.FormatDouble(3.14);
    Debug.WriteLine("FormatDouble: " + s);
    s := (3.14).ToString;
    Debug.WriteLine("ToString: " + s);
    s := CF.FormatDateEx(DateTime.Now, "dddd, MM/yyyy");
    Debug.WriteLine("FormatDateEx: " + s);
    s := (DateTime.Now).ToString;
    Debug.WriteLine("ToString: " + s);
End Sub UserProc;

After executing the example the console window displays results of converting real number and date considering and not considering regional settings and operating system.

Results of executing the example in Russian Windows:

Module execution started
FormatDouble: 3,14
ToString: 3.1400000000000001
FormatDateEx: Thursday, 06/2010
ToString: 10.06.2010 16:10:50
Module execution finished

Results of executing the example in English Windows:

Module execution started
FormatDouble: 3.14
ToString: 3.1400000000000001
FormatDateEx: Thursday, 06/2010
ToString: 10.06.2010 16:10:58
Module execution finished