Definition of an attribute of an OGRFeatureDefn. More...

#include <ogr_feature.h>

Public Member Functions
	OGRFieldDefn (const char *, OGRFieldType)
	Constructor.

	OGRFieldDefn (const OGRFieldDefn *)
	Constructor.

void	SetName (const char *)
	Reset the name of this field.

const char *	GetNameRef () const
	Fetch name of this field.

void	SetAlternativeName (const char *)
	Reset the alternative name (or "alias") for this field.

const char *	GetAlternativeNameRef () const
	Fetch the alternative name (or "alias") for this field.

OGRFieldType	GetType () const
	Fetch type of this field.

void	SetType (OGRFieldType eTypeIn)
	Set the type of this field.

OGRFieldSubType	GetSubType () const
	Fetch subtype of this field.

void	SetSubType (OGRFieldSubType eSubTypeIn)
	Set the subtype of this field.

OGRJustification	GetJustify () const
	Get the justification for this field.

void	SetJustify (OGRJustification eJustifyIn)
	Set the justification for this field.

int	GetWidth () const
	Get the formatting width for this field.

void	SetWidth (int nWidthIn)
	Set the formatting width for this field in characters.

int	GetPrecision () const
	Get the formatting precision for this field.

void	SetPrecision (int nPrecisionIn)
	Set the formatting precision for this field in characters.

int	GetTZFlag () const
	Get the time zone flag.

void	SetTZFlag (int nTZFlag)
	Set the time zone flag.

void	Set (const char *, OGRFieldType, int=0, int=0, OGRJustification=OJUndefined)
	Set defining parameters for a field in one call.

void	SetDefault (const char *)
	Set default field value.

const char *	GetDefault () const
	Get default field value.

int	IsDefaultDriverSpecific () const
	Returns whether the default value is driver specific.

int	IsIgnored () const
	Return whether this field should be omitted when fetching features.

void	SetIgnored (int bIgnoreIn)
	Set whether this field should be omitted when fetching features.

int	IsNullable () const
	Return whether this field can receive null values.

void	SetNullable (int bNullableIn)
	Set whether this field can receive null values.

int	IsUnique () const
	Return whether this field has a unique constraint.

void	SetUnique (int bUniqueIn)
	Set whether this field has a unique constraint.

const std::string &	GetDomainName () const
	Return the name of the field domain for this field.

void	SetDomainName (const std::string &osDomainName)
	Set the name of the field domain for this field.

const std::string &	GetComment () const
	Return the (optional) comment for this field.

void	SetComment (const std::string &osComment)
	Set the comment for this field.

int	IsSame (const OGRFieldDefn *) const
	Test if the field definition is identical to the other one.

void	Seal ()
	Seal a OGRFieldDefn.

void	Unseal ()
	Unseal a OGRFieldDefn.

TemporaryUnsealer	GetTemporaryUnsealer ()
	Return an object that temporary unseals the OGRFieldDefn.

Static Public Member Functions
static const char *	GetFieldTypeName (OGRFieldType)
	Fetch human readable name for a field type.

static const char *	GetFieldSubTypeName (OGRFieldSubType)
	Fetch human readable name for a field subtype.

static OGRFieldDefnH	ToHandle (OGRFieldDefn *poFieldDefn)
	Convert a OGRFieldDefn* to a OGRFieldDefnH.

static OGRFieldDefn *	FromHandle (OGRFieldDefnH hFieldDefn)
	Convert a OGRFieldDefnH to a OGRFieldDefn*.

Detailed Description

Definition of an attribute of an OGRFeatureDefn.

A field is described by :

a name. See SetName() / GetNameRef()
an alternative name (optional): alternative descriptive name for the field (sometimes referred to as an "alias"). See SetAlternativeName() / GetAlternativeNameRef()
a type: OFTString, OFTInteger, OFTReal, ... See SetType() / GetType()
a subtype (optional): OFSTBoolean, ... See SetSubType() / GetSubType()
a width (optional): maximal number of characters. See SetWidth() / GetWidth()
a precision (optional): number of digits after decimal point. See SetPrecision() / GetPrecision()
a NOT NULL constraint (optional). See SetNullable() / IsNullable()
a UNIQUE constraint (optional). See SetUnique() / IsUnique()
a default value (optional). See SetDefault() / GetDefault()
a boolean to indicate whether it should be ignored when retrieving features. See SetIgnored() / IsIgnored()
a field domain name (optional). See SetDomainName() / Get DomainName()

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn().

Constructor & Destructor Documentation

◆ OGRFieldDefn() [1/2]

OGRFieldDefn::OGRFieldDefn	(	const char *	pszNameIn,
		OGRFieldType	eTypeIn
	)

Constructor.

By default, fields have no width, precision, are nullable and not ignored.

Parameters

pszNameIn	the name of the new field.
eTypeIn	the type of the new field.

◆ OGRFieldDefn() [2/2]

OGRFieldDefn::OGRFieldDefn ( const OGRFieldDefn * poPrototype )

explicit

Constructor.

Create by cloning an existing field definition.

Parameters

poPrototype the field definition to clone.

Member Function Documentation

◆ FromHandle()

static OGRFieldDefn * OGRFieldDefn::FromHandle ( OGRFieldDefnH hFieldDefn )

inlinestatic

Convert a OGRFieldDefnH to a OGRFieldDefn*.

Since: GDAL 2.3

◆ GetAlternativeNameRef()

const char * OGRFieldDefn::GetAlternativeNameRef ( ) const

inline

Fetch the alternative name (or "alias") for this field.

The alternative name is an optional attribute for a field which can provide a more user-friendly, descriptive name of a field which is not subject to the usual naming constraints defined by the data provider.

This is a metadata style attribute only: the alternative name cannot be used in place of the actual field name during SQL queries or other field name dependent API calls.

This method is the same as the C function OGR_Fld_GetAlternativeNameRef().

Returns: pointer to an internal alternative name string that should not be freed or modified.

Since: GDAL 3.2

◆ GetComment()

const std::string & OGRFieldDefn::GetComment ( ) const

inline

Return the (optional) comment for this field.

By default, none (empty string) is returned.

This method is the same as the C function OGR_Fld_GetComment().

Returns: the field comment, or an empty string if there is none.

Since: GDAL 3.7

◆ GetDefault()

const char * OGRFieldDefn::GetDefault ( ) const

Get default field value.

This function is the same as the C function OGR_Fld_GetDefault().

Returns: default field value or NULL.

Since: GDAL 2.0

◆ GetDomainName()

const std::string & OGRFieldDefn::GetDomainName ( ) const

inline

Return the name of the field domain for this field.

By default, none (empty string) is returned.

Field domains (OGRFieldDomain class) are attached at the GDALDataset level and should be retrieved with GDALDataset::GetFieldDomain().

This method is the same as the C function OGR_Fld_GetDomainName().

Returns: the field domain name, or an empty string if there is none.

Since: GDAL 3.3

◆ GetFieldSubTypeName()

const char * OGRFieldDefn::GetFieldSubTypeName ( OGRFieldSubType eSubType )

static

Fetch human readable name for a field subtype.

This static method is the same as the C function OGR_GetFieldSubTypeName().

Parameters

eSubType the field subtype to get name for.

Returns: pointer to an internal static name string. It should not be modified or freed.

Since: GDAL 2.0

◆ GetFieldTypeName()

const char * OGRFieldDefn::GetFieldTypeName ( OGRFieldType eType )

static

Fetch human readable name for a field type.

This static method is the same as the C function OGR_GetFieldTypeName().

Parameters

eType the field type to get name for.

Returns: pointer to an internal static name string. It should not be modified or freed.

◆ GetJustify()

OGRJustification OGRFieldDefn::GetJustify ( ) const

inline

Get the justification for this field.

Note: no driver is know to use the concept of field justification.

This method is the same as the C function OGR_Fld_GetJustify().

Returns: the justification.

◆ GetNameRef()

const char * OGRFieldDefn::GetNameRef ( ) const

inline

Fetch name of this field.

This method is the same as the C function OGR_Fld_GetNameRef().

Returns: pointer to an internal name string that should not be freed or modified.

◆ GetPrecision()

int OGRFieldDefn::GetPrecision ( ) const

inline

Get the formatting precision for this field.

This should normally be zero for fields of types other than OFTReal.

This method is the same as the C function OGR_Fld_GetPrecision().

Returns: the precision.

◆ GetSubType()

OGRFieldSubType OGRFieldDefn::GetSubType ( ) const

inline

Fetch subtype of this field.

This method is the same as the C function OGR_Fld_GetSubType().

Returns: field subtype.

Since: GDAL 2.0

◆ GetTemporaryUnsealer()

OGRFieldDefn::TemporaryUnsealer OGRFieldDefn::GetTemporaryUnsealer ( )

Return an object that temporary unseals the OGRFieldDefn.

The returned object calls Unseal() initially, and when it is destroyed it calls Seal().

This method should only be called by driver implementations.

It is also possible to use the helper method whileUnsealing(). Example: whileUnsealing(poFieldDefn)->some_method()

Since: GDAL 3.9

◆ GetType()

OGRFieldType OGRFieldDefn::GetType ( ) const

inline

Fetch type of this field.

This method is the same as the C function OGR_Fld_GetType().

Returns: field type.

◆ GetTZFlag()

int OGRFieldDefn::GetTZFlag ( ) const

inline

Get the time zone flag.

Only applies to OFTTime, OFTDate and OFTDateTime fields.

Cf OGR_TZFLAG_UNKNOWN, OGR_TZFLAG_LOCALTIME, OGR_TZFLAG_MIXED_TZ and OGR_TZFLAG_UTC

This method is the same as the C function OGR_Fld_GetTZFlag().

Returns: the time zone flag.

Since: GDAL 3.8

◆ GetWidth()

int OGRFieldDefn::GetWidth ( ) const

inline

Get the formatting width for this field.

This method is the same as the C function OGR_Fld_GetWidth().

Returns: the width, zero means no specified width.

◆ IsDefaultDriverSpecific()

int OGRFieldDefn::IsDefaultDriverSpecific ( ) const

Returns whether the default value is driver specific.

Driver specific default values are those that are not NULL, a numeric value, a literal value enclosed between single quote characters, CURRENT_TIMESTAMP, CURRENT_TIME, CURRENT_DATE or datetime literal value.

This method is the same as the C function OGR_Fld_IsDefaultDriverSpecific().

Returns: TRUE if the default value is driver specific.

Since: GDAL 2.0

◆ IsIgnored()

int OGRFieldDefn::IsIgnored ( ) const

inline

Return whether this field should be omitted when fetching features.

This method is the same as the C function OGR_Fld_IsIgnored().

Returns: ignore state

◆ IsNullable()

int OGRFieldDefn::IsNullable ( ) const

inline

Return whether this field can receive null values.

By default, fields are nullable.

Even if this method returns FALSE (i.e not-nullable field), it doesn't mean that OGRFeature::IsFieldSet() will necessary return TRUE, as fields can be temporary unset and null/not-null validation is usually done when OGRLayer::CreateFeature()/SetFeature() is called.

This method is the same as the C function OGR_Fld_IsNullable().

Returns: TRUE if the field is authorized to be null.

Since: GDAL 2.0

◆ IsSame()

int OGRFieldDefn::IsSame ( const OGRFieldDefn * poOtherFieldDefn ) const

Test if the field definition is identical to the other one.

Parameters

poOtherFieldDefn the other field definition to compare to.

Returns: TRUE if the field definition is identical to the other one.

◆ IsUnique()

int OGRFieldDefn::IsUnique ( ) const

inline

Return whether this field has a unique constraint.

By default, fields have no unique constraint.

This method is the same as the C function OGR_Fld_IsUnique().

Returns: TRUE if the field has a unique constraint.

Since: GDAL 3.2

◆ Seal()

void OGRFieldDefn::Seal ( )

Seal a OGRFieldDefn.

A sealed OGRFieldDefn can not be modified while it is sealed.

This method should only be called by driver implementations.

Since: GDAL 3.9

◆ Set()

void OGRFieldDefn::Set	(	const char *	pszNameIn,
		OGRFieldType	eTypeIn,
		int	nWidthIn = `0`,
		int	nPrecisionIn = `0`,
		OGRJustification	eJustifyIn = `OJUndefined`
	)

Set defining parameters for a field in one call.

This method is the same as the C function OGR_Fld_Set().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Parameters

pszNameIn	the new name to assign.
eTypeIn	the new type (one of the OFT values like OFTInteger).
nWidthIn	the preferred formatting width. Defaults to zero indicating undefined.
nPrecisionIn	number of decimals places for formatting, defaults to zero indicating undefined.
eJustifyIn	the formatting justification (OJLeft or OJRight), defaults to OJUndefined.

◆ SetAlternativeName()

void OGRFieldDefn::SetAlternativeName ( const char * pszAlternativeNameIn )

Reset the alternative name (or "alias") for this field.

The alternative name is an optional attribute for a field which can provide a more user-friendly, descriptive name of a field which is not subject to the usual naming constraints defined by the data provider.

This is a metadata style attribute only: the alternative name cannot be used in place of the actual field name during SQL queries or other field name dependent API calls.

This method is the same as the C function OGR_Fld_SetAlternativeName().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Parameters

pszAlternativeNameIn the new alternative name to apply.

Since: GDAL 3.2

◆ SetComment()

void OGRFieldDefn::SetComment ( const std::string & osComment )

Set the comment for this field.

This method is the same as the C function OGR_Fld_SetComment().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn().

Parameters

osComment Field comment.

Since: GDAL 3.7

◆ SetDefault()

void OGRFieldDefn::SetDefault ( const char * pszDefaultIn )

Set default field value.

The default field value is taken into account by drivers (generally those with a SQL interface) that support it at field creation time. OGR will generally not automatically set the default field value to null fields by itself when calling OGRFeature::CreateFeature() / OGRFeature::SetFeature(), but will let the low-level layers to do the job. So retrieving the feature from the layer is recommended.

The accepted values are NULL, a numeric value, a literal value enclosed between single quote characters (and inner single quote characters escaped by repetition of the single quote character), CURRENT_TIMESTAMP, CURRENT_TIME, CURRENT_DATE or a driver specific expression (that might be ignored by other drivers). For a datetime literal value, format should be 'YYYY/MM/DD HH:MM:SS[.sss]' (considered as UTC time).

Drivers that support writing DEFAULT clauses will advertise the GDAL_DCAP_DEFAULT_FIELDS driver metadata item.

This function is the same as the C function OGR_Fld_SetDefault().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Parameters

pszDefaultIn new default field value or NULL pointer.

Since: GDAL 2.0

◆ SetDomainName()

void OGRFieldDefn::SetDomainName ( const std::string & osDomainName )

Set the name of the field domain for this field.

Field domains (OGRFieldDomain) are attached at the GDALDataset level.

This method is the same as the C function OGR_Fld_SetDomainName().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn().

Parameters

osDomainName Field domain name.

Since: GDAL 3.3

◆ SetIgnored()

void OGRFieldDefn::SetIgnored ( int ignore )

inline

Set whether this field should be omitted when fetching features.

This method is the same as the C function OGR_Fld_SetIgnored().

This method should not be called on a object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, the OGRLayer::SetIgnoredFields() method should be called.

Parameters

ignore ignore state

◆ SetJustify()

void OGRFieldDefn::SetJustify ( OGRJustification eJustify )

inline

Set the justification for this field.

Note: no driver is know to use the concept of field justification.

This method is the same as the C function OGR_Fld_SetJustify().

Parameters

eJustify the new justification.

◆ SetName()

void OGRFieldDefn::SetName ( const char * pszNameIn )

Reset the name of this field.

This method is the same as the C function OGR_Fld_SetName().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Parameters

pszNameIn the new name to apply.

◆ SetNullable()

void OGRFieldDefn::SetNullable ( int bNullableIn )

Set whether this field can receive null values.

By default, fields are nullable, so this method is generally called with FALSE to set a not-null constraint.

Drivers that support writing not-null constraint will advertise the GDAL_DCAP_NOTNULL_FIELDS driver metadata item.

This method is the same as the C function OGR_Fld_SetNullable().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn().

Parameters

bNullableIn FALSE if the field must have a not-null constraint.

Since: GDAL 2.0

◆ SetPrecision()

void OGRFieldDefn::SetPrecision ( int nPrecisionIn )

Set the formatting precision for this field in characters.

This should normally be zero for fields of types other than OFTReal.

This method is the same as the C function OGR_Fld_SetPrecision().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Parameters

nPrecisionIn the new precision.

◆ SetSubType()

void OGRFieldDefn::SetSubType ( OGRFieldSubType eSubTypeIn )

Set the subtype of this field.

This should never be done to an OGRFieldDefn that is already part of an OGRFeatureDefn.

This method is the same as the C function OGR_Fld_SetSubType().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Parameters

eSubTypeIn the new field subtype.

Since: GDAL 2.0

◆ SetType()

void OGRFieldDefn::SetType ( OGRFieldType eTypeIn )

Set the type of this field.

This should never be done to an OGRFieldDefn that is already part of an OGRFeatureDefn.

This method is the same as the C function OGR_Fld_SetType().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Parameters

eTypeIn the new field type.

◆ SetTZFlag()

void OGRFieldDefn::SetTZFlag ( int nTZFlag )

Set the time zone flag.

Only applies to OFTTime, OFTDate and OFTDateTime fields.

Cf OGR_TZFLAG_UNKNOWN, OGR_TZFLAG_LOCALTIME, OGR_TZFLAG_MIXED_TZ and OGR_TZFLAG_UTC

This method is the same as the C function OGR_Fld_SetTZFlag().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Parameters

nTZFlag the new time zone flag.

Since: GDAL 3.8

◆ SetUnique()

void OGRFieldDefn::SetUnique ( int bUniqueIn )

Set whether this field has a unique constraint.

By default, fields have no unique constraint, so this method is generally called with TRUE to set a unique constraint.

Drivers that support writing unique constraint will advertise the GDAL_DCAP_UNIQUE_FIELDS driver metadata item.

This method is the same as the C function OGR_Fld_SetUnique().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn().

Parameters

bUniqueIn TRUE if the field must have a unique constraint.

Since: GDAL 3.2

◆ SetWidth()

void OGRFieldDefn::SetWidth ( int nWidthIn )

Set the formatting width for this field in characters.

This method is the same as the C function OGR_Fld_SetWidth().

Note that once a OGRFieldDefn has been added to a layer definition with OGRLayer::AddFieldDefn(), its setter methods should not be called on the object returned with OGRLayer::GetLayerDefn()->GetFieldDefn(). Instead, OGRLayer::AlterFieldDefn() should be called on a new instance of OGRFieldDefn, for drivers that support AlterFieldDefn.

Parameters

nWidthIn the new width.

◆ ToHandle()

static OGRFieldDefnH OGRFieldDefn::ToHandle ( OGRFieldDefn * poFieldDefn )

inlinestatic

Convert a OGRFieldDefn* to a OGRFieldDefnH.

Since: GDAL 2.3

◆ Unseal()

void OGRFieldDefn::Unseal ( )

Unseal a OGRFieldDefn.

Undo OGRFieldDefn::Seal()

Using GetTemporaryUnsealer() is recommended for most use cases.

This method should only be called by driver implementations.

Since: GDAL 3.9

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

ogr_feature.h
ogrfielddefn.cpp

Public Member Functions

Static Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ OGRFieldDefn() [1/2]

◆ OGRFieldDefn() [2/2]

Member Function Documentation

◆ FromHandle()

◆ GetAlternativeNameRef()

◆ GetComment()

◆ GetDefault()

◆ GetDomainName()

◆ GetFieldSubTypeName()

◆ GetFieldTypeName()

◆ GetJustify()

◆ GetNameRef()

◆ GetPrecision()

◆ GetSubType()

◆ GetTemporaryUnsealer()

◆ GetType()

◆ GetTZFlag()

◆ GetWidth()

◆ IsDefaultDriverSpecific()

◆ IsIgnored()

◆ IsNullable()

◆ IsSame()

◆ IsUnique()

◆ Seal()

◆ Set()

◆ SetAlternativeName()

◆ SetComment()

◆ SetDefault()

◆ SetDomainName()

◆ SetIgnored()

◆ SetJustify()

◆ SetName()

◆ SetNullable()

◆ SetPrecision()

◆ SetSubType()

◆ SetType()

◆ SetTZFlag()

◆ SetUnique()

◆ SetWidth()

◆ ToHandle()

◆ Unseal()