Preferences

Overview

The Preferences module provides APIs for key-value (KV) data processing, including querying, modifying, and persisting KV data.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Since: 13

Summary

Files

Name	Description
oh_preferences.h	Provides APIs and structs for accessing the Preferences object.
oh_preferences_err_code.h	Defines the error codes used in the Preferences module.
oh_preferences_option.h	Provides APIs and structs for accessing the PreferencesOption object.
oh_preferences_value.h	Provides APIs, enums, and structs for accessing the PreferencesValue object.

Types

Name	Description
typedef struct OH_Preferences OH_Preferences	Defines a struct for a Preferences object.
typedef void(* OH_PreferencesDataObserver) (void *context, const OH_PreferencesPair *pairs, uint32_t count)	Defines a struct for the callback for data changes.
typedef enum OH_Preferences_ErrCode OH_Preferences_ErrCode	Defines an enum for error codes.
typedef struct OH_PreferencesOption OH_PreferencesOption	Defines a struct for Preferences configuration.
typedef enum Preference_ValueType Preference_ValueType	Defines an enum for types of PreferencesValue.
typedef struct OH_PreferencesPair OH_PreferencesPair	Defines a struct for the Preferences data in KV format.
typedef struct OH_PreferencesValue OH_PreferencesValue	Defines the struct for a PreferencesValue object.
typedef enum Preferences_StorageType Preferences_StorageType	Defines an enum for preferences storage types.

Enums

Name	Description
OH_Preferences_ErrCode { PREFERENCES_OK = 0, PREFERENCES_ERROR_INVALID_PARAM = 401, PREFERENCES_ERROR_NOT_SUPPORTED = 801, PREFERENCES_ERROR_BASE = 15500000, PREFERENCES_ERROR_DELETE_FILE = 15500010, PREFERENCES_ERROR_STORAGE = 15500011, PREFERENCES_ERROR_MALLOC = 15500012, PREFERENCES_ERROR_KEY_NOT_FOUND = 15500013, PREFERENCES_ERROR_GET_DATAOBSMGRCLIENT = 15500019 }	Enumerates the error codes.
Preference_ValueType { PREFERENCE_TYPE_NULL = 0, PREFERENCE_TYPE_INT, PREFERENCE_TYPE_BOOL, PREFERENCE_TYPE_STRING, PREFERENCE_TYPE_BUTT }	Enumerates the types of PreferencesValue.
Preferences_StorageType { PREFERENCES_STORAGE_XML = 0, PREFERENCES_STORAGE_GSKV }	Enumerates the preferences storage types.

Functions

Name	Description
int OH_PreferencesOption_SetStorageType (OH_PreferencesOption *option, Preferences_StorageType type)	Sets the storage type for a preferences instance.
int OH_Preferences_IsStorageTypeSupported (Preferences_StorageType type, bool *isSupported)	Checks whether the specified storage type is supported.
OH_Preferences * OH_Preferences_Open (OH_PreferencesOption *option, int *errCode)	Opens a Preferences instance and creates a pointer to it. If the pointer is no longer required, use [OH_Preferences_Close]OH_Preferences_Close to close the instance.
int OH_Preferences_Close (OH_Preferences *preference)	Closes a Preferences instance.
int OH_Preferences_GetInt (OH_Preferences *preference, const char *key, int *value)	Obtains an integer corresponding to the specified key in a Preferences instance.
int OH_Preferences_GetBool (OH_Preferences *preference, const char *key, bool *value)	Obtains a Boolean value corresponding to the specified key in a Preferences instance.
int OH_Preferences_GetString (OH_Preferences *preference, const char *key, char **value, uint32_t *valueLen)	Obtains a string corresponding to the specified key in a Preferences instance.
void OH_Preferences_FreeString (char *string)	Releases a string.
int OH_Preferences_SetInt (OH_Preferences *preference, const char *key, int value)	Sets an integer based on the specified key in a Preferences instance.
int OH_Preferences_SetBool (OH_Preferences *preference, const char *key, bool value)	Sets a Boolean value based on the specified key in a Preferences instance.
int OH_Preferences_SetString (OH_Preferences *preference, const char *key, const char *value)	Sets a string based on the specified key in a Preferences instance.
int OH_Preferences_Delete (OH_Preferences *preference, const char *key)	Deletes the KV data corresponding to the specified key from a Preferences instance.
int OH_Preferences_RegisterDataObserver (OH_Preferences *preference, void *context, OH_PreferencesDataObserver observer, const char *keys[], uint32_t keyCount)	Subscribes to data changes of the specified keys. If the value of the specified key changes, a callback will be invoked after OH_Preferences_Close () is called.
int OH_Preferences_UnregisterDataObserver (OH_Preferences *preference, void *context, OH_PreferencesDataObserver observer, const char *keys[], uint32_t keyCount)	Unsubscribes from data changes of the specified keys.
OH_PreferencesOption * OH_PreferencesOption_Create (void)	Creates an OH_PreferencesOption instance and a pointer to it. If this pointer is no longer required, use OH_PreferencesOption_Destroy to destroy it. Otherwise, memory leaks may occur.
int OH_PreferencesOption_SetFileName (OH_PreferencesOption *option, const char *fileName)	Sets the file name for an OH_PreferencesOption instance.
int OH_PreferencesOption_SetBundleName (OH_PreferencesOption *option, const char *bundleName)	Sets the bundle name for an OH_PreferencesOption instance.
int OH_PreferencesOption_SetDataGroupId (OH_PreferencesOption *option, const char *dataGroupId)	Sets the application group ID for an OH_PreferencesOption instance.
int OH_PreferencesOption_Destroy (OH_PreferencesOption *option)	Destroys an OH_PreferencesOption instance.
const char * OH_PreferencesPair_GetKey (const OH_PreferencesPair *pairs, uint32_t index)	Obtains the key based on the specified index from the KV data.
const OH_PreferencesValue * OH_PreferencesPair_GetPreferencesValue (const OH_PreferencesPair *pairs, uint32_t index)	Obtains the value based on the specified index from the KV pairs.
Preference_ValueType OH_PreferencesValue_GetValueType (const OH_PreferencesValue *object)	Obtains the data type of a PreferencesValue instance.
int OH_PreferencesValue_GetInt (const OH_PreferencesValue *object, int *value)	Obtains an integer value from an OH_PreferencesValue instance.
int OH_PreferencesValue_GetBool (const OH_PreferencesValue *object, bool *value)	Obtains a Boolean value from an OH_PreferencesValue instance.
int OH_PreferencesValue_GetString (const OH_PreferencesValue *object, char **value, uint32_t *valueLen)	Obtains a string from an OH_PreferencesValue instance.

Type Description

Preferences_StorageType

typedef enum Preferences_StorageType Preferences_StorageType

Description

Defines an enum for preferences storage types.

Since: 18

OH_Preferences

typedef struct OH_Preferences OH_Preferences

Description

Represents a Preferences object.

Since: 13

OH_Preferences_ErrCode

typedef enum OH_Preferences_ErrCode OH_Preferences_ErrCode

Description

Defines an enum for error codes.

Since: 13

OH_PreferencesDataObserver

typedef void(*OH_PreferencesDataObserver) (void *context, const OH_PreferencesPair *pairs, uint32_t count)

Description

Defines a struct for the callback used to return data changes.

Since: 13

Parameters

Name	Description
context	Pointer to the application context.
pairs	Pointer to the changed KV data.
count	Number of KV pairs changed.

See

OH_PreferencesPair

OH_PreferencesOption

typedef struct OH_PreferencesOption OH_PreferencesOption

Description

Defines a struct for Preferences configuration.

Since: 13

OH_PreferencesPair

typedef struct OH_PreferencesPair OH_PreferencesPair

Description

Defines a struct for the Preferences data in KV format.

Since: 13

OH_PreferencesValue

typedef struct OH_PreferencesValue OH_PreferencesValue

Description

Defines the struct for a PreferencesValue object.

Since: 13

Preference_ValueType

typedef enum Preference_ValueType Preference_ValueType

Description

Defines an enum for types of PreferencesValue.

Since: 13

Enum Description

Preferences_StorageType

enum Preferences_StorageType

Description

Enumerates the preferences storage types.

Since: 18

Enumerated Value	Description
PREFERENCES_STORAGE_XML	XML. In this type is used, data operations are performed in the memory and data is persisted after OH_Preferences_Close is called. This type does not multi-processes operations.
PREFERENCES_STORAGE_GSKV	CLKV. If this type is used, data operations are flushed on a real-time basis. This type supports multi-process operations.

OH_Preferences_ErrCode

enum OH_Preferences_ErrCode

Description

Enumerates the error codes.

Since: 13

Enumerated Value	Description
PREFERENCES_OK	The operation is successful.
PREFERENCES_ERROR_INVALID_PARAM	Invalid parameter.
PREFERENCES_ERROR_NOT_SUPPORTED	The system capability is not supported.
PREFERENCES_ERROR_BASE	Base error code.
PREFERENCES_ERROR_DELETE_FILE	Failed to delete the file.
PREFERENCES_ERROR_STORAGE	The storage is abnormal.
PREFERENCES_ERROR_MALLOC	Failed to allocate memory.
PREFERENCES_ERROR_KEY_NOT_FOUND	The key does not exist.
PREFERENCES_ERROR_GET_DATAOBSMGRCLIENT	Failed to obtain the data change subscription service.

Preference_ValueType

enum Preference_ValueType

Description

Enumerates the types of PreferencesValue.

Since: 13

Enumerated Value	Description
PREFERENCE_TYPE_NULL	Null.
PREFERENCE_TYPE_INT	Integer.
PREFERENCE_TYPE_BOOL	Boolean.
PREFERENCE_TYPE_STRING	String.
PREFERENCE_TYPE_BUTT	End type.

Function Description

OH_Preferences_IsStorageTypeSupported()

int OH_Preferences_IsStorageTypeSupported (Preferences_StorageType type, bool *isSupported )

Description

Checks whether the specified storage type is supported.

Since: 18

Parameters

Name	Description
type	Storage type to check.
isSupported	Pointer to the check result. The value true means the storage type is supported; the value false means the opposite.

Returns

Returns the operation status code.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

OH_PreferencesOption_SetStorageType()

int OH_PreferencesOption_SetStorageType (OH_PreferencesOption *option, Preferences_StorageType type )

Description

Sets the storage type for a preferences instance.

Since: 18

Parameters

Name	Description
option	Pointer to the configuration whose storage type is to set.
type	Storage type to set.

Returns

Returns the error code.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

See

OH_PreferencesOption.

OH_Preferences_Close()

int OH_Preferences_Close (OH_Preferences *preference)

Description

Closes a Preferences instance.

Since: 13

Parameters

Name	Description
preference	Pointer to the OH_Preferences instance to close.

Returns

Returns OH_Preferences_ErrCode.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

PREFERENCES_ERROR_STORAGE indicates the storage is abnormal.

PREFERENCES_ERROR_MALLOC indicates a failure in memory allocation.

See

OH_Preferences

OH_Preferences_ErrCode

OH_Preferences_Delete()

int OH_Preferences_Delete (OH_Preferences *preference, const char *key )

Description

Deletes the KV data corresponding to the specified key from a Preferences instance.

Since: 13

Parameters

Name	Description
preference	Pointer to the target OH_Preferences instance.
key	Pointer to the key of the KV pair to delete.

Returns

Returns the error code.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

PREFERENCES_ERROR_STORAGE indicates the storage is abnormal.

PREFERENCES_ERROR_MALLOC indicates a failure in memory allocation.

See

OH_Preferences

OH_Preferences_ErrCode

OH_Preferences_FreeString()

void OH_Preferences_FreeString (char *string)

Description

Releases a string.

Since: 13

Parameters

Name	Description
string	Pointer to the string to release.

See

OH_Preferences

OH_Preferences_GetBool()

int OH_Preferences_GetBool (OH_Preferences *preference, const char *key, bool *value )

Description

Obtains a Boolean value corresponding to the specified key in a Preferences instance.

Since: 13

Parameters

Name	Description
preference	Pointer to the target OH_Preferences instance.
key	Pointer to the key of the value to obtain.
value	Pointer to the Boolean value obtained.

Returns

Returns the error code.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

PREFERENCES_ERROR_STORAGE indicates the storage is abnormal.

PREFERENCES_ERROR_MALLOC indicates a failure in memory allocation.

PREFERENCES_ERROR_KEY_NOT_FOUND indicates that the specified key does not exist.

See

OH_Preferences

OH_Preferences_ErrCode

OH_Preferences_GetInt()

int OH_Preferences_GetInt (OH_Preferences *preference, const char *key, int *value )

Description

Obtains an integer corresponding to the specified key in a Preferences instance.

Since: 13

Parameters

Name	Description
preference	Pointer to the target OH_Preferences instance.
key	Pointer to the key of the value to obtain.
value	Pointer to the integer value obtained.

Returns

Returns the error code.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

PREFERENCES_ERROR_STORAGE indicates the storage is abnormal.

PREFERENCES_ERROR_MALLOC indicates a failure in memory allocation.

PREFERENCES_ERROR_KEY_NOT_FOUND indicates that the specified key does not exist.

See

OH_Preferences

OH_Preferences_ErrCode

OH_Preferences_GetString()

int OH_Preferences_GetString (OH_Preferences *preference, const char *key, char **value, uint32_t *valueLen )

Description

Obtains a string corresponding to the specified key in a Preferences instance.

Since: 13

Parameters

Name	Description
preference	Pointer to the target OH_Preferences instance.
key	Pointer to the key of the value to obtain.
value	Double pointer to the string obtained. If the string is not required, you can use OH_Preferences_FreeString to free the string (release the memory occupied by the string).
valueLen	Pointer to the length of the string obtained.

Returns

Returns the error code.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

PREFERENCES_ERROR_STORAGE indicates the storage is abnormal.

PREFERENCES_ERROR_MALLOC indicates a failure in memory allocation.

PREFERENCES_ERROR_KEY_NOT_FOUND indicates that the specified key does not exist.

See

OH_Preferences

OH_Preferences_ErrCode

OH_Preferences_Open()

OH_Preferences* OH_Preferences_Open (OH_PreferencesOption *option, int *errCode )

Description

Opens a Preferences instance and creates a pointer to it. If the pointer is no longer required, use OH_Preferences_Close to close the instance.

Since: 13

Parameters

Name	Description
option	Pointer to the OH_PreferencesOption instance.
errCode	Pointer to the error code returned. For details, see OH_Preferences_ErrCode.

Returns

Returns the OH_Preferences instance opened if the operation is successful; returns a null pointer otherwise.

See

OH_Preferences

OH_PreferencesOption

OH_Preferences_ErrCode

OH_Preferences_RegisterDataObserver()

int OH_Preferences_RegisterDataObserver (OH_Preferences *preference, void *context, OH_PreferencesDataObserver observer, const char *keys[], uint32_t keyCount )

Description

Subscribes to data changes of the specified keys. If the value of the specified key changes, a callback will be invoked after OH_Preferences_Close () is called.

Since: 13

Parameters

Name	Description
preference	Pointer to the target OH_Preferences instance.
context	Pointer to the application context.
observer	OH_PreferencesDataObserver callback to be invoked when the data changes.
keys	Pointer to the keys of the data to be observed.
keyCount	Number of keys observed.

Returns

Returns the error code.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

PREFERENCES_ERROR_STORAGE indicates the storage is abnormal.

PREFERENCES_ERROR_MALLOC indicates a failure in memory allocation.

PREFERENCES_ERROR_GET_DATAOBSMGRCLIENT indicates a failure in obtaining the data change subscription service.

See

OH_Preferences

OH_PreferencesDataObserver

OH_Preferences_ErrCode

OH_Preferences_SetBool()

int OH_Preferences_SetBool (OH_Preferences *preference, const char *key, bool value )

Description

Sets a Boolean value based on the specified key in a Preferences instance.

Since: 13

Parameters

Name	Description
preference	Pointer to the target OH_Preferences instance.
key	Pointer to the key of the value to set.
value	Boolean value to be set.

Returns

Returns the error code.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

PREFERENCES_ERROR_STORAGE indicates the storage is abnormal.

PREFERENCES_ERROR_MALLOC indicates a failure in memory allocation.

See

OH_Preferences

OH_Preferences_ErrCode

OH_Preferences_SetInt()

int OH_Preferences_SetInt (OH_Preferences *preference, const char *key, int value )

Description

Sets an integer based on the specified key in a Preferences instance.

Since: 13

Parameters

Name	Description
preference	Pointer to the target OH_Preferences instance.
key	Pointer to the key of the value to set.
value	Integer value to be set.

Returns

Returns the error code.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

PREFERENCES_ERROR_STORAGE indicates the storage is abnormal.

PREFERENCES_ERROR_MALLOC indicates a failure in memory allocation.

See

OH_Preferences

OH_Preferences_ErrCode

OH_Preferences_SetString()

int OH_Preferences_SetString (OH_Preferences *preference, const char *key, const char *value )

Description

Sets a string based on the specified key in a Preferences instance.

Since: 13

Parameters

Name	Description
preference	Pointer to the target OH_Preferences instance.
key	Pointer to the key of the value to set.
value	Pointer to the string to set.

Returns

Returns the error code.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

PREFERENCES_ERROR_STORAGE indicates the storage is abnormal.

PREFERENCES_ERROR_MALLOC indicates a failure in memory allocation.

See

OH_Preferences

OH_Preferences_ErrCode

OH_Preferences_UnregisterDataObserver()

int OH_Preferences_UnregisterDataObserver (OH_Preferences *preference, void *context, OH_PreferencesDataObserver observer, const char *keys[], uint32_t keyCount )

Description

Unsubscribes from data changes of the specified keys.

Since: 13

Parameters

Name	Description
preference	Pointer to the target OH_Preferences instance.
context	Pointer to the application context.
observer	OH_PreferencesDataObserver callback to unregister.
keys	Pointer to the keys of the values whose changes are not observed.
keyCount	Number of keys.

Returns

Returns the error code.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

PREFERENCES_ERROR_STORAGE indicates the storage is abnormal.

PREFERENCES_ERROR_MALLOC indicates a failure in memory allocation.

See

OH_Preferences

OH_PreferencesDataObserver

OH_Preferences_ErrCode

OH_PreferencesOption_Create()

OH_PreferencesOption* OH_PreferencesOption_Create (void )

Description

Creates an OH_PreferencesOption instance and a pointer to it.
If this pointer is no longer required, use OH_PreferencesOption_Destroy to destroy it. Otherwise, memory leaks may occur.

Since: 13

Returns

Returns a pointer to the OH_PreferencesOption instance created if the operation is successful; returns a null pointer otherwise.

See

OH_PreferencesOption

OH_PreferencesOption_Destroy()

int OH_PreferencesOption_Destroy (OH_PreferencesOption *option)

Description

Destroys an OH_PreferencesOption instance.

Since: 13

Parameters

Name	Description
option	Pointer to the OH_PreferencesOption instance to destroy.

Returns

Returns the error code.
PREFERENCES_OK indicates the operation is successful.
PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

See

OH_PreferencesOption

OH_Preferences_ErrCode

OH_PreferencesOption_SetBundleName()

int OH_PreferencesOption_SetBundleName (OH_PreferencesOption *option, const char *bundleName )

Description

Sets the bundle name for an OH_PreferencesOption instance.

Since: 13

Parameters

Name	Description
option	Pointer to the target OH_PreferencesOption instance.
bundleName	Pointer to the bundle name to set.

Returns

Returns the error code.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

See

OH_PreferencesOption

OH_Preferences_ErrCode

OH_PreferencesOption_SetDataGroupId()

int OH_PreferencesOption_SetDataGroupId (OH_PreferencesOption *option, const char *dataGroupId )

Description

Sets the application group ID for an OH_PreferencesOption instance.

After the application group ID is set, the Preferences instance will be created in the sandbox directory of the application group ID.

The application group ID must be obtained from AppGallery. This parameter is not supported currently.

If the application group ID is an empty string, the Preferences instance will be created in the sandbox directory of the current application.

Since: 13

Parameters

Name	Description
option	Pointer to the target OH_PreferencesOption instance.
dataGroupId	Pointer to the application group ID to set.

Returns

Returns the error code.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

See

OH_PreferencesOption

OH_Preferences_ErrCode

OH_PreferencesOption_SetFileName()

int OH_PreferencesOption_SetFileName (OH_PreferencesOption *option, const char *fileName )

Description

Sets the file name for an OH_PreferencesOption instance.

Since: 13

Parameters

Name	Description
option	Pointer to the target OH_PreferencesOption instance.
fileName	Pointer to the file name to set.

Returns

Returns the error code.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

See

OH_PreferencesOption

OH_Preferences_ErrCode

OH_PreferencesPair_GetKey()

const char* OH_PreferencesPair_GetKey (const OH_PreferencesPair *pairs, uint32_t index )

Description

Obtains the key based on the specified index from the KV data.

Since: 13

Parameters

Name	Description
pairs	Pointer to the target OH_PreferencesPair.
index	Index of the target OH_PreferencesPair.

Returns

Returns the pointer to the key obtained if the operation is successful.

Returns a null pointer if the operation fails or the input parameter is invalid.

See

OH_PreferencesPair

OH_PreferencesPair_GetPreferencesValue()

const OH_PreferencesValue* OH_PreferencesPair_GetPreferencesValue (const OH_PreferencesPair *pairs, uint32_t index )

Description

Obtains the value based on the specified index from the KV pairs.

Since: 13

Parameters

Name	Description
pairs	Pointer to the target OH_PreferencesPair.
index	Index of the target OH_PreferencesPair.

Returns

Returns the pointer to the value obtained if the operation is successful.
Returns a null pointer if the operation fails or the input parameter is invalid.

See

OH_PreferencesValue

OH_PreferencesValue_GetBool()

int OH_PreferencesValue_GetBool (const OH_PreferencesValue *object, bool *value )

Description

Obtains a Boolean value from an OH_PreferencesValue instance.

Since: 13

Parameters

Name	Description
object	Pointer to the target OH_PreferencesValue instance.
value	Pointer to the Boolean value obtained.

Returns

Returns the error code.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

PREFERENCES_ERROR_STORAGE indicates the storage is abnormal.

PREFERENCES_ERROR_MALLOC indicates a failure in memory allocation.

See

OH_PreferencesValue

OH_Preferences_ErrCode

OH_PreferencesValue_GetInt()

int OH_PreferencesValue_GetInt (const OH_PreferencesValue* object, int* value )

Description

Obtains an integer from an OH_PreferencesValue instance.

Since: 13

Parameters

Name	Description
object	Pointer to the target OH_PreferencesValue instance.
value	Pointer to the integer value obtained.

Returns

Returns the error code.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

PREFERENCES_ERROR_STORAGE indicates the storage is abnormal.

PREFERENCES_ERROR_MALLOC indicates a failure in memory allocation.

See

OH_PreferencesValue

OH_Preferences_ErrCode

OH_PreferencesValue_GetString()

int OH_PreferencesValue_GetString (const OH_PreferencesValue *object, char **value, uint32_t *valueLen )

Description

Obtains a string from an OH_PreferencesValue instance.

Since: 13

Parameters

Name	Description
object	Pointer to the target OH_PreferencesValue instance.
value	Double pointer to the string obtained. If the string is not required, you can use OH_Preferences_FreeString to free the string (release the memory occupied by the string).
valueLen	Pointer to the length of the string obtained.

Returns

Returns the error code.

PREFERENCES_OK indicates the operation is successful.

PREFERENCES_ERROR_INVALID_PARAM indicates invalid parameters are specified.

PREFERENCES_ERROR_STORAGE indicates the storage is abnormal.

PREFERENCES_ERROR_MALLOC indicates a failure in memory allocation.

See

OH_PreferencesValue

OH_Preferences_ErrCode

OH_PreferencesValue_GetValueType()

Preference_ValueType OH_PreferencesValue_GetValueType (const OH_PreferencesValue *object)

Description

Obtains the data type of a PreferencesValue instance.

Since: 13

Parameters

Name	Description
object	Pointer to the target OH_PreferencesValue instance.

Returns

Returns the obtained data type. If PREFERENCE_TYPE_NULL is returned, invalid parameter is passed in.

See

OH_PreferencesValue

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