# Unit Class Reference

A unit for measurement. More...

`#include <Unit.h>`

Inheritance diagram for Unit:

List of all members.

## Public Member Functions

| Unit (string cat_, string name_, string plural_="", string singular_="", string title_="", bool is_local=true, bool is_builtin=false, bool is_active=true)
| Unit (const Unit *unit)
virtual ExpressionItem * | copy () const
virtual void | set (const ExpressionItem *item)
bool | isSIUnit () const
void | setAsSIUnit ()
void | setSystem (string s_system)
const string & | system () const
bool | isCurrency () const
virtual string | print (bool plural_, bool short_, bool use_unicode=false, bool(*can_display_unicode_string_function)(const char *, void *)=NULL, void *can_display_unicode_string_arg=NULL) const
virtual const string & | plural (bool return_singular_if_no_plural=true, bool use_unicode=false, bool(*can_display_unicode_string_function)(const char *, void *)=NULL, void *can_display_unicode_string_arg=NULL) const
virtual const string & | singular (bool return_abbreviation_if_no_singular=true, bool use_unicode=false, bool(*can_display_unicode_string_function)(const char *, void *)=NULL, void *can_display_unicode_string_arg=NULL) const
virtual const string & | abbreviation (bool return_singular_if_no_abbreviation=true, bool use_unicode=false, bool(*can_display_unicode_string_function)(const char *, void *)=NULL, void *can_display_unicode_string_arg=NULL) const
virtual bool | isUsedByOtherUnits () const
virtual Unit * | baseUnit () const
virtual MathStructure & | convertToBaseUnit (MathStructure &mvalue, MathStructure &mexp) const
virtual MathStructure & | convertFromBaseUnit (MathStructure &mvalue, MathStructure &mexp) const
virtual MathStructure & | convertToBaseUnit (MathStructure &mvalue) const
virtual MathStructure & | convertFromBaseUnit (MathStructure &mvalue) const
virtual MathStructure | convertToBaseUnit () const
virtual MathStructure | convertFromBaseUnit () const
virtual int | baseExponent (int exp=1) const
virtual int | type () const
virtual int | subtype () const
virtual bool | isChildOf (Unit *u) const
virtual bool | isParentOf (Unit *u) const
virtual bool | hasComplexRelationTo (Unit *u) const
bool | convert (Unit *u, MathStructure &mvalue, MathStructure &exp) const
bool | convert (Unit *u, MathStructure &mvalue) const
MathStructure | convert (Unit *u, bool *converted=NULL) const

## Protected Attributes

string | ssystem
bool | b_si

## Detailed Description

A unit for measurement.

The Unit class both represents a base unit and is the base class for other unit types. Base units are units defined as basis for other units. Meters and seconds are typical base units.

For base units, a name is all that is needed. Base units do however normally have three different names defined for use in expressions - abbreviation (ex. "m"), singular ("meter") and plural ("meters").

## Member Function Documentation

bool Unit::isSIUnit | ( |  | ) | const

Returns if the unit is part of the SI standard.

Returns:
  true if the unit is part of the SI standard.

void Unit::setAsSIUnit | ( |  | ) |

State that the unit is part of the SI standard. Sets system to "SI".

void Unit::setSystem | ( | string | s_system | ) |

Sets which system/standard ("SI", "SGC", etc.) the unit is part of. Setting system to "SI" (case-insensitive), is equivalent to setAsSIUnit().

const string& Unit::system | ( |  | ) | const

Returns the system/standard that the unit is part of.

Returns:
  System string.

bool Unit::isCurrency | ( |  | ) | const

Returns if the unit is a currency (Euro is base unit).

Returns:
  true if the unit is a currency.

virtual string Unit::print | ( | bool | plural_,
|  | bool | short_,
|  | bool | use_unicode = `false`,
|  | bool(*)(const char *, void *) | can_display_unicode_string_function = `NULL`,
|  | void * | can_display_unicode_string_arg = `NULL` |
| ) |  |  | const`[virtual]`

Returns a display string representing the unit in an expression.

Equivalent to preferredName() for Unit and AliasUnit, but closer to MathStructure::print() for CompositeUnit (prints out base expression).

Reimplemented in AliasUnit_Composite, and CompositeUnit.

virtual int Unit::type | ( |  | ) | const`[virtual]`

Returns the type of the expression item, corresponding to which subclass the object belongs to.

Returns:
  ExpressionItemType.

Implements ExpressionItem.

virtual int Unit::subtype | ( |  | ) | const`[virtual]`

Returns the subtype of the unit, corresponding to which subsubclass the object belongs to.

Returns:
  UnitSubtype.

Implements ExpressionItem.

Reimplemented in AliasUnit, and CompositeUnit.

virtual bool Unit::isChildOf | ( | Unit * | u | ) | const`[virtual]`

If specified unit is a base unit for this unit, directly or with other units in between. Equivalent to u->isParentOf(this).

Reimplemented in AliasUnit.

virtual bool Unit::isParentOf | ( | Unit * | u | ) | const`[virtual]`

If this unit is a base unit for specified unit, directly or with other units in between. Equivalent to u->isChildOf(this).

Reimplemented in AliasUnit.

bool Unit::convert | ( | Unit * | u,
|  | MathStructure & | mvalue,
|  | MathStructure & | exp |
| ) |  |  | const

Converts a value from specified unit and exponent to this unit. value * (unit^exponent) = new value * (this^new exponent) This function cannot convert to or from CompositeUnit.

Parameters:

  | u | Unit to convert from.
  `[in,out]` | mvalue | Quantity value.
  `[in,out]` | exp | Exponent.

Returns:
  true if the value was successfully converted.

bool Unit::convert | ( | Unit * | u,
|  | MathStructure & | mvalue |
| ) |  |  | const

Converts a value from specified unit and exponent to this unit. value * unit = new value * this This function cannot convert to or from CompositeUnit.

Parameters:

  | u | Unit to convert from.
  `[in,out]` | mvalue | Quantity value.

Returns:
  true if the value was successfully converted.

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

- libqalculate/Unit.h