| Type |  | Name |  | Summary | 
|  | 
| Compiler Directive |  | $D |  | Determines whether application debug information is built | 
| Compiler Directive |  | $DebugInfo |  | Determines whether application debug information is built | 
| Compiler Directive |  | $Define |  | Defines a compiler directive symbol - as used by IfDef | 
| Compiler Directive |  | $DefinitionInfo |  | Determines whether application symbol information is built | 
| Function |  | Date |  | Gives the current date | 
| Variable |  | DateSeparator |  | The character used to separate display date fields | 
| Function |  | DateTimeToFileDate |  | Convert a TDateTime value to a File date/time format | 
| Function |  | DateTimeToStr |  | Converts TDateTime date and time values to a string | 
| Procedure |  | DateTimeToString |  | Rich formatting of a TDateTime variable into a string | 
| Function |  | DateToStr |  | Converts a TDateTime date value to a string | 
| Function |  | DayOfTheMonth |  | Gives day of month index for a TDateTime value (ISO 8601) | 
| Function |  | DayOfTheWeek |  | Gives day of week index for a TDateTime value (ISO 8601) | 
| Function |  | DayOfTheYear |  | Gives the day of the year for a TDateTime value (ISO 8601) | 
| Function |  | DayOfWeek |  | Gives day of week index for a TDateTime value | 
| Function |  | DaysBetween |  | Gives the whole number of days between 2 dates | 
| Function |  | DaysInAMonth |  | Gives the number of days in a month | 
| Function |  | DaysInAYear |  | Gives the number of days in a year | 
| Function |  | DaySpan |  | Gives the fractional number of days between 2 dates | 
| Procedure |  | Dec |  | Decrement an ordinal variable | 
| Variable |  | DecimalSeparator |  | The character used to display the decimal point | 
| Procedure |  | DecodeDate |  | Extracts the year, month, day values from a TDateTime var. | 
| Procedure |  | DecodeDateTime |  | Breaks a TDateTime variable into its date/time parts | 
| Procedure |  | DecodeTime |  | Break a TDateTime value into individual time values | 
| Directive |  | Default |  | Defines default processing for a property | 
| Function |  | DegToRad |  | Convert a degrees value to radians | 
| Procedure |  | Delete |  | Delete a section of characters from a string | 
| Function |  | DeleteFile |  | Delete a file specified by its file name | 
| Keyword |  | Destructor |  | Defines the method used to destroy an object | 
| Function |  | DirectoryExists |  | Returns true if the given directory exists | 
| Function |  | DiskFree |  | Gives the number of free bytes on a specified drive | 
| Function |  | DiskSize |  | Gives the size in bytes of a specified drive | 
| Procedure |  | Dispose |  | Dispose of storage used by a  pointer type variable | 
| Keyword |  | Div |  | Performs integer division, discarding the remainder | 
| Keyword |  | Do |  | Defines the start of some controlled action | 
| Type |  | Double |  | A floating point type supporting about 15 digits of precision | 
| Keyword |  | DownTo |  | Prefixes an decremental for loop target value | 
| Function |  | DupeString |  | Creates a string containing copies of a substring | 
| Directive |  | Dynamic |  | Allows a class method to be overriden in derived classes | 
|  |