utl::Decimal Class Reference

Fixed-point decimal number. More...

#include <Decimal.h>

Inheritance diagram for utl::Decimal:

Public Member Functions

 Decimal (int64_t n)
 Constructor. More...
 Decimal (const String &str)
 Constructor. More...
virtual void copy (const Object &rhs)
 Copy another instance. More...
virtual int compare (const Object &rhs) const
 Compare with another object. More...
virtual void serialize (Stream &stream, uint_t io, uint_t mode=ser_default)
 Serialize to or from a stream. More...
virtual String toString () const
 Return a string representation of self. More...
String toString (uint_t digits, bool round=true) const
 Convert to string representation. More...
Decimalset (const String &str)
 Set from string representation. More...
Decimalabs ()
 Take the absolute value. More...
Decimalfloor ()
 Remove any fractional component. More...
Math Operators
Decimal operator+ (const Decimal &rhs) const
Decimaloperator+= (const Decimal &rhs)
Decimal operator- (const Decimal &rhs) const
Decimaloperator-= (const Decimal &rhs)
Decimal operator* (const Decimal &rhs) const
Decimaloperator*= (const Decimal &rhs)
Decimal operator/ (const Decimal &rhs) const
Decimaloperator/= (const Decimal &rhs)
Decimal operator% (const Decimal &rhs) const
Decimaloperator++ ()
Decimal operator++ (int)
Decimaloperator-- ()
Decimal operator-- (int)
- Public Member Functions inherited from utl::Object
void clear ()
 Revert to initial state. More...
virtual void vclone (const Object &rhs)
 Make an exact copy of another instance. More...
virtual void steal (Object &rhs)
 "Steal" the internal representation from another instance. More...
virtual void dump (Stream &os, uint_t level=uint_t_max) const
 Dump a human-readable representation of self to the given output stream. More...
void dumpWithClassName (Stream &os, uint_t indent=4, uint_t level=uint_t_max) const
 Front-end for dump() that prints the object's class name. More...
virtual const ObjectgetKey () const
 Get the key for this object. More...
bool hasKey () const
 Determine whether or not the object has a key. More...
virtual const ObjectgetProxiedObject () const
 Get the proxied object (= self if none). More...
virtual ObjectgetProxiedObject ()
 Get the proxied object (= self if none). More...
virtual size_t hash (size_t size) const
 Get the hash code for the object. More...
bool _isA (const RunTimeClass *runTimeClass) const
 Determine whether self's class is a descendent of the given class. More...
 operator String () const
 Conversion to String. More...
size_t allocatedSize () const
 Get the total allocated size of this object. More...
virtual size_t innerAllocatedSize () const
 Get the "inner" allocated size. More...
virtual void addOwnedIt (const class FwdIt *it) const
 Notify self that it owns the given iterator. More...
virtual void removeOwnedIt (const class FwdIt *it) const
 Notify self that the given owned iterator has been destroyed. More...
bool operator< (const Object &rhs) const
 Less-than operator. More...
bool operator<= (const Object &rhs) const
 Less-than-or-equal-to operator. More...
bool operator> (const Object &rhs) const
 Greater-than operator. More...
bool operator>= (const Object &rhs) const
 Greater-than-or-equal-to operator. More...
bool operator== (const Object &rhs) const
 Equal-to operator. More...
bool operator!= (const Object &rhs) const
 Unequal-to operator. More...
void serializeIn (Stream &is, uint_t mode=ser_default)
 Serialize from an input stream. More...
void serializeOut (Stream &os, uint_t mode=ser_default) const
 Serialize to an output stream. More...
void serializeOutBoxed (Stream &os, uint_t mode=ser_default) const
 Serialize a boxed object to an output stream. More...

Additional Inherited Members

- Static Public Member Functions inherited from utl::Object
static ObjectserializeInNullable (Stream &is, uint_t mode=ser_default)
 Serialize a nullptr-able object from an input stream. More...
static void serializeOutNullable (const Object *object, Stream &os, uint_t mode=ser_default)
 Serialize a nullptr-able object to an output stream. More...
static void serializeNullable (Object *&object, Stream &stream, uint_t io, uint_t mode=ser_default)
 Serialize a nullptr-able object to or from a stream. More...
static ObjectserializeInBoxed (Stream &is, uint_t mode=ser_default)
 Serialize a boxed object from an input stream. More...
static void serializeBoxed (Object *&object, Stream &stream, uint_t io, uint_t mode=ser_default)
 Serialize a boxed object to or from a stream. More...

Detailed Description

Fixed-point decimal number.

This simple implementation uses a signed 64-bit integer as the raw encoding, and provides 6 decimal digits of precision. That is, the fractional part of the decimal number may be precisely expressed as a whole number of one-millionths.

Noting that:

  • the decimal number is stored in a signed 64-bit integer
  • 6 decimal digits of precision are provided
  • size of the space of 64-bit values: 18,446,744,073,709,551,616.
  • half the above size is: 9,223,372,036,854,775,808.

We get:

  • minimum representable value: -9,223,372,036,854.775808
  • maximum representable value: +9,223,372,036,854.775807

Addition and subtraction are simple: just add or subtract the "raw" underlying integers, and the result of that is the correct decimal answer.

Multiplication and division are very simple too, but they do need a simple shift adjustment to restore correct scaling factor, as well as a rounding adjustment to minimize loss of precision when extra digits in the result of a calculation are discarded. For example, 2/3 will be calculated as 0.666667 (and not 0.666666).

Note that if you call toString() with digits < 6, the printed number may be rounded up to show the closest approximation to the actual stored number in the specified number of digits:

Decimal a("0.999999"), b("0.66899");
cout << a.toString(2) << endl; // outputs "1.00" !
cout << b.toString(2) << endl; // outputs "0.67"

If you don't want this behavior, specify round=false when calling toString().

Adam McKee

Definition at line 57 of file Decimal.h.

Constructor & Destructor Documentation

◆ Decimal() [1/2]

utl::Decimal::Decimal ( int64_t  n)


ninitial value

Definition at line 66 of file Decimal.h.

◆ Decimal() [2/2]

utl::Decimal::Decimal ( const String str)


strstring representation of initial value

Definition at line 75 of file Decimal.h.

References utl::compare(), utl::copy(), utl::ser_default, utl::serialize(), and utl::toString().

Member Function Documentation

◆ copy()

virtual void utl::Decimal::copy ( const Object rhs)

Copy another instance.

When you override copy(), you should usually call the superclass's copy().

rhsobject to copy

Reimplemented from utl::Object.

◆ compare()

virtual int utl::Decimal::compare ( const Object rhs) const

Compare with another object.

If no overridden version succeeds in doing the comparison, then an attempt will be made to re-start the comparison process using one or both of the objects' keys. Usually, an override of compare() should call the superclass's compare() if it doesn't know how to compare itself with the rhs object.

See also
< 0 if self < rhs, 0 if self = rhs, > 0 if self > rhs
rhsobject to compare with

Reimplemented from utl::Object.

◆ serialize()

virtual void utl::Decimal::serialize ( Stream stream,
uint_t  io,
uint_t  mode = ser_default 

Serialize to or from a stream.

This is the only virtual method for serialization. You must override this in any class that has data to be serialized, and ensure that the superclass's serialize() gets called.

streamstream to serialize from/to
iosee utl::io_t
modesee utl::serialize_t

Reimplemented from utl::Object.

◆ toString() [1/2]

virtual String utl::Decimal::toString ( ) const

Return a string representation of self.

Reimplemented from utl::Object.

◆ toString() [2/2]

String utl::Decimal::toString ( uint_t  digits,
bool  round = true 
) const

Convert to string representation.

digitsnumber of digits of precision
round(optional : true) round up to show best approximation (if digits < 6)?

◆ set()

Decimal& utl::Decimal::set ( const String str)

Set from string representation.

◆ abs()

Decimal& utl::Decimal::abs ( )

Take the absolute value.

Definition at line 100 of file Decimal.h.

◆ floor()

Decimal& utl::Decimal::floor ( )

Remove any fractional component.

Definition at line 108 of file Decimal.h.

References utl::deInit(), and utl::init().

The documentation for this class was generated from the following file: