Delphi Basics : RTL by Unit : System

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Type	Name	Summary

Function	Abs	Gives the absolute value of a number (-ve sign is removed)
Variable	AbstractErrorProc	Defines a proc called when an abstract method is called
Function	Addr	Gives the address of a variable, function or procedure
Type	AnsiChar	A character type guaranteed to be 8 bits in size
Type	AnsiString	A data type that holds a string of AnsiChars
Procedure	Append	Open a text file to allow appending of text to the end
Function	ArcTan	The Arc Tangent of a number, returned in radians
Procedure	Assign	Assigns a file handle to a binary or text file
Function	Assigned	Returns true if a reference is not nil
Procedure	AssignFile	Assigns a file handle to a binary or text file
Function	BeginThread	Begins a separate thread of code execution
Procedure	BlockRead	Reads a block of data records from an untyped binary file
Procedure	BlockWrite	Writes a block of data records to an untyped binary file
Type	Boolean	Allows just True and False values
Procedure	Break	Forces a jump out of a single loop
Type	Byte	An integer type supporting values 0 to 255
Type	Cardinal	The basic unsigned integer type
Type	Char	Variable type holding a single character
Procedure	ChDir	Change the working drive plus path for a specified drive
Function	Chr	Convert an integer into a character
Procedure	Close	Closes an open file
Procedure	CloseFile	Closes an open file
Variable	CmdLine	Holds the execution text used to start the current program
Type	Comp	A 64 bit signed integer
Function	Concat	Concatenates one or more strings into one string
Procedure	Continue	Forces a jump to the next iteration of a loop
Function	Copy	Create a copy of part of a string or an array
Function	Cos	The Cosine of a number
Type	Currency	A floating point type with 4 decimals used for financial values
Procedure	Dec	Decrement an ordinal variable
Procedure	Delete	Delete a section of characters from a string
Procedure	Dispose	Dispose of storage used by a pointer type variable
Type	Double	A floating point type supporting about 15 digits of precision
Procedure	EndThread	Terminates a thread with an exit code
Function	Eof	Returns true if a file opened with Reset is at the end
Function	Eoln	Returns true if the current text file is pointing at a line end
Procedure	Erase	Erase a file
Variable	ErrorAddr	Sets the error address when an application terminates
Procedure	Exclude	Exclude a value in a set variable
Procedure	Exit	Exit abruptly from a function or procedure
Variable	ExitCode	Sets the return code when an application terminates
Function	Exp	Gives the exponent of a number
Directive	Export	Makes a function or procedure in a DLL externally available
Type	Extended	The floating point type with the highest capacity and precision
Variable	FileMode	Defines how Reset opens a binary file
Function	FilePos	Gives the file position in a binary or text file
Function	FileSize	Gives the size in records of an open file
Procedure	FillChar	Fills out a section of storage with a fill character or byte value
Procedure	Flush	Flushes buffered text file data to the file
Function	Frac	The fractional part of a floating point number
Procedure	FreeMem	Free memory storage used by a variable
Keyword	Function	Defines a subroutine that returns a value
Procedure	GetDir	Get the default directory (drive plus path) for a specified drive
Function	GetLastError	Gives the error code of the last failing Windows API call
Function	GetMem	Get a specified number of storage bytes
Procedure	Halt	Terminates the program with an optional dialog
Function	Hi	Returns the hi-order byte of a (2 byte) Integer
Function	High	Returns the highest value of a type or variable
Procedure	Inc	Increment an ordinal variable
Procedure	Include	Include a value in a set variable
Variable	Input	Defines the standard input text file
Procedure	Insert	Insert a string into another string
Function	Int	The integer part of a floating point number as a float
Type	Int64	A 64 bit sized integer - the largest in Delphi
Type	Integer	The basic Integer type
Keyword	Interface	Used for Unit external definitions, and as a Class skeleton
Function	IOResult	Holds the return code of the last I/O operation
Function	IsMultiThread	Returns true if the code is running multiple threads
Function	Length	Return the number of elements in an array or string
Function	Ln	Gives the natural logarithm of a number
Function	Lo	Returns the low-order byte of a (2 byte) Integer
Type	LongInt	An Integer whose size is guaranteed to be 32 bits
Type	LongWord	A 32 bit unsigned integer
Function	Low	Returns the lowest value of a type or variable
Constant	MaxInt	The maximum value an Integer can have
Constant	MaxLongInt	The maximum value an LongInt can have
Procedure	MkDir	Make a directory
Procedure	Move	Copy bytes of data from a source to a destination
Procedure	New	Create a new pointer type variable
Constant	Nil	A pointer value that is defined as undetermined
Keyword	Object	Allows a subroutine data type to refer to an object method
Function	Odd	Tests whether an integer has an odd value
Function	Ord	Provides the Ordinal value of an integer, character or enum
Variable	Output	Defines the standard output text file
Type	PAnsiChar	A pointer to an AnsiChar value
Type	PAnsiString	Pointer to an AnsiString value
Function	ParamCount	Gives the number of parameters passed to the current program
Function	ParamStr	Returns one of the parameters used to run the current program
Type	PChar	A pointer to an Char value
Type	PCurrency	Pointer to a Currency value
Type	PDateTime	Pointer to a TDateTime value
Type	PExtended	Pointer to a Extended floating point value
Function	Pi	The mathematical constant
Type	PInt64	Pointer to an Int64 value
Type	Pointer	Defines a general use Pointer to any memory based data
Function	Pos	Find the position of one string in another
Function	Pred	Decrement an ordinal variable
Keyword	Procedure	Defines a subroutine that does not return a value
Keyword	Program	Defines the start of an application
Keyword	Property	Defines controlled access to class fields
Type	PShortString	A pointer to an ShortString value
Type	PString	Pointer to a String value
Type	PVariant	Pointer to a Variant value
Type	PWideChar	Pointer to a WideChar
Type	PWideString	Pointer to a WideString value
Function	Random	Generate a random floating point or integer number
Procedure	Randomize	Reposition the Random number generator next value
Variable	RandSeed	Reposition the Random number generator next value
Procedure	Read	Read data from a binary or text file
Procedure	ReadLn	Read a complete line of data from a text file
Type	Real	A floating point type supporting about 15 digits of precision
Type	Real48	The floating point type with the highest capacity and precision
Procedure	ReallocMem	Reallocate an existing block of storage
Procedure	Rename	Rename a file
Procedure	Reset	Open a text file for reading, or binary file for read/write
Variable	Result	A variable used to hold the return value from a function
Procedure	ReWrite	Open a text or binary file for write access
Procedure	RmDir	Remove a directory
Function	Round	Rounds a floating point number to an integer
Procedure	RunError	Terminates the program with an error dialog
Procedure	Seek	Move the pointer in a binary file to a new record position
Function	SeekEof	Skip to the end of the current line or file
Function	SeekEoln	Skip to the end of the current line or file
Variable	Self	Hidden parameter to a method - refers to the containing object
Procedure	SetLength	Changes the size of a string, or the size(s) of an array
Procedure	SetString	Copies characters from a buffer into a string
Type	ShortInt	An integer type supporting values -128 to 127
Type	ShortString	Defines a string of up to 255 characters
Function	Sin	The Sine of a number
Type	Single	The smallest capacity and precision floating point type
Function	SizeOf	Gives the storage byte size of a type or variable
Function	Slice	Creates a slice of an array as an Open Array parameter
Type	SmallInt	An Integer type supporting values from -32768 to 32767
Function	Sqr	Gives the square of a number
Function	Sqrt	Gives the square root of a number
Procedure	Str	Converts an integer or floating point number to a string
Type	String	A data type that holds a string of characters
Function	StringOfChar	Creates a string with one character repeated many times
Function	StringToWideChar	Converts a normal string into a WideChar 0 terminated buffer
Function	Succ	Increment an ordinal variable
Type	TDateTime	Data type holding a date and time value
Type	Text	Defines a file as a text file
Type	TextFile	Declares a file type for storing lines of text
Type	TObject	The base class type that is ancestor to all other classes
Function	Trunc	The integer part of a floating point number
Procedure	Truncate	Truncates a file size - removes all data after the current position
Type	TThreadFunc	Defines the function to be called by BeginThread
Function	UpCase	Convert a Char value to upper case
Procedure	Val	Converts number strings to integer and floating point values
Type	Variant	A variable type that can hold changing data types
Type	WideChar	Variable type holding a single International character
Function	WideCharToString	Copies a null terminated WideChar string to a normal string
Type	WideString	A data type that holds a string of WideChars
Type	Word	An integer type supporting values 0 to 65535
Procedure	Write	Write data to a binary or text file
Procedure	WriteLn	Write a complete line of data to a text file

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