A single Value: GNOME Data Access 5 manual

## A single Value A single Value — Assorted functions for dealing with GValue values |

## Stability Level

Stable, unless otherwise indicated

## Functions

GValue * | gda_value_new ()
#define | GDA_VALUE_HOLDS_NULL()
#define | GDA_VALUE_HOLDS_DEFAULT()
#define | GDA_VALUE_HOLDS_BINARY()
#define | GDA_VALUE_HOLDS_BLOB()
#define | GDA_VALUE_HOLDS_GEOMETRIC_POINT()
#define | GDA_VALUE_HOLDS_NUMERIC()
#define | GDA_VALUE_HOLDS_SHORT()
#define | GDA_VALUE_HOLDS_USHORT()
#define | GDA_VALUE_HOLDS_TIME()
#define | GDA_VALUE_HOLDS_TIMESTAMP()
GValue * | gda_value_new_null ()
void | gda_value_set_null ()
GValue * | gda_value_new_default ()
GValue * | gda_value_copy ()
void | gda_value_free ()
GValue * | gda_value_new_from_string ()
gboolean | gda_value_set_from_string ()
gboolean | gda_value_set_from_value ()
gchar * | gda_value_stringify ()
gint | gda_value_differ ()
gint | gda_value_compare ()
GValue * | gda_value_new_from_xml ()
xmlNodePtr | gda_value_to_xml ()
void | gda_value_reset_with_type ()
gboolean | gda_value_is_null ()
gboolean | gda_value_is_number ()
#define | gda_value_isa()
GValue * | gda_value_new_binary ()
const GdaBinary * | gda_value_get_binary ()
void | gda_value_set_binary ()
void | gda_value_take_binary ()
gpointer | gda_binary_copy ()
void | gda_binary_free ()
gchar * | gda_binary_to_string ()
GdaBinary * | gda_string_to_binary ()
GValue * | gda_value_new_blob ()
GValue * | gda_value_new_blob_from_file ()
gpointer | gda_blob_copy ()
void | gda_blob_free ()
const GdaBlob * | gda_value_get_blob ()
void | gda_value_set_blob ()
void | gda_value_take_blob ()
void | gda_blob_set_op ()
gchar * | gda_blob_to_string ()
gpointer | gda_geometricpoint_copy ()
void | gda_geometricpoint_free ()
const GdaGeometricPoint * | gda_value_get_geometric_point ()
void | gda_value_set_geometric_point ()
GdaNumeric * | gda_numeric_new ()
GdaNumeric * | gda_numeric_copy ()
void | gda_numeric_free ()
gchar * | gda_numeric_get_string ()
gdouble | gda_numeric_get_double ()
glong | gda_numeric_get_precision ()
glong | gda_numeric_get_width ()
void | gda_numeric_set_double ()
void | gda_numeric_set_from_string ()
void | gda_numeric_set_precision ()
void | gda_numeric_set_width ()
const GdaNumeric * | gda_value_get_numeric ()
void | gda_value_set_numeric ()
gpointer | gda_time_copy ()
void | gda_time_free ()
gboolean | gda_time_valid ()
void | gda_time_change_timezone ()
const GdaTime * | gda_value_get_time ()
void | gda_value_set_time ()
gpointer | gda_timestamp_copy ()
void | gda_timestamp_free ()
gboolean | gda_timestamp_valid ()
void | gda_timestamp_change_timezone ()
const GdaTimestamp * | gda_value_get_timestamp ()
void | gda_value_set_timestamp ()
GValue * | gda_value_new_timestamp_from_timet ()
gshort | gda_value_get_short ()
void | gda_value_set_short ()
gushort | gda_value_get_ushort ()
void | gda_value_set_ushort ()

## Types and Values

enum | GdaValueAttribute
#define | GDA_TYPE_NULL
#define | GDA_TYPE_DEFAULT
#define | GDA_TYPE_BINARY
#define | GDA_TYPE_BLOB
#define | GDA_TYPE_GEOMETRIC_POINT
#define | GDA_TYPE_NUMERIC
#define | GDA_TYPE_SHORT
#define | GDA_TYPE_USHORT
#define | GDA_TYPE_TIME
#define | GDA_TYPE_TIMESTAMP
| GdaBinary
| GdaBlob
| GdaGeometricPoint
struct | GdaNumeric
| GdaTime
| GdaTimestamp

## Object Hierarchy

        GBoxed
        ├── GdaBinary
        ├── GdaGeometricPoint
        ├── GdaNumeric
        ├── GdaTime
        ╰── GdaTimestamp

## Includes

    #include <libgda/gda-blob-op.h>

## Description

Libgda manages each individual value within an opaque GValue structure. Any GValue type can be used, and Libgda adds a few more data types usually found in DBMS such as NUMERIC, TIME, TIMESTAMP, GEOMETRIC POINT, BINARY and BLOB.

Libgda makes a distinction between binary and blob types

- binary data can be inserted into an SQL statement using a (DBMS dependent) syntax, such as "X'ABCD'" syntax for SQLite or the binary strings syntax for PostgreSQL. Binary data is manipulated using a GdaBinary structure (which is basically a bytes buffer and a length attribute).

- blob data are a special feature that some DBMS have which requires some non SQL code to manipulate them. Usually only a reference is stored in each table containing a blob, and the actual blob data resides somewhere on the disk (while still being managed transparently by the database). For example PotsgreSQL stores blobs as files on the disk and references them using object identifiers (Oid). Blob data is manipulated using a GdaBlob structure which encapsulates a GdaBinary structure and adds a reference to a GdaBlobOp object used to read and write data from and to the blob.

Please note that is distinction between binary data and blobs is Libgda only and does not reflect the DBMS's documentations; for instance MySQL has several BLOB types but Libgda interprets them as binary types.

Each provider or connection can be queried about its blob support using the `gda_server_provider_supports_feature()` or `gda_connection_supports_feature()` methods.

There are two special value types which are:

- the GDA_TYPE_NULL value which never changes and acutally represents an SQL NULL value

- the GDA_TYPE_DEFAULT value which represents a default value which Libgda does not interpret (such as when a table column's default value is a function call)

## Functions

### gda_value_new ()

    GValue *
    gda_value_new (GType type);

Makes a new GValue of type `type` .

[skip]

#### Parameters

type | the new value type. |

#### Returns

the newly created GValue with the specified `type` . You need to set the value in the returned GValue.

Free-function: gda_value_free.

[transfer full]

### GDA_VALUE_HOLDS_NULL()

    #define             GDA_VALUE_HOLDS_NULL(value)

### GDA_VALUE_HOLDS_DEFAULT()

    #define             GDA_VALUE_HOLDS_DEFAULT(value)

### GDA_VALUE_HOLDS_BINARY()

    #define             GDA_VALUE_HOLDS_BINARY(value)

### GDA_VALUE_HOLDS_BLOB()

    #define             GDA_VALUE_HOLDS_BLOB(value)

### GDA_VALUE_HOLDS_GEOMETRIC_POINT()

    #define             GDA_VALUE_HOLDS_GEOMETRIC_POINT(value)

### GDA_VALUE_HOLDS_NUMERIC()

    #define             GDA_VALUE_HOLDS_NUMERIC(value)

### GDA_VALUE_HOLDS_SHORT()

    #define             GDA_VALUE_HOLDS_SHORT(value)

### GDA_VALUE_HOLDS_USHORT()

    #define             GDA_VALUE_HOLDS_USHORT(value)

### GDA_VALUE_HOLDS_TIME()

    #define             GDA_VALUE_HOLDS_TIME(value)

### GDA_VALUE_HOLDS_TIMESTAMP()

    #define             GDA_VALUE_HOLDS_TIMESTAMP(value)

### gda_value_new_null ()

    GValue *
    gda_value_new_null (void);

Creates a new GValue initiated to a GdaNull structure with a GDA_TYPE_NULL, to represent a NULL in the database.

[skip]

#### Returns

a new GValue of the type GDA_TYPE_NULL.

[transfer full]

### gda_value_set_null ()

    void
    gda_value_set_null (GValue *value);

Sets the type of `value` to GDA_TYPE_NULL.

[skip]

#### Parameters

value | a GValue that will store a value of type GDA_TYPE_NULL. |

### gda_value_new_default ()

    GValue *
    gda_value_new_default (const gchar *default_val);

Creates a new default value.

[skip]

#### Parameters

default_val | the default value as a string, or `NULL`. | [nullable]

#### Returns

a new GValue of the type GDA_TYPE_DEFAULT.

[transfer full]

Since: 4.2.9

### gda_value_copy ()

    GValue *
    gda_value_copy (const GValue *value);

Creates a new GValue from an existing one.

[skip]

#### Parameters

value | value to get a copy from. |

#### Returns

a newly allocated GValue with a copy of the data in `value` .

Free-function: gda_value_free.

[transfer full]

### gda_value_free ()

    void
    gda_value_free (GValue *value);

Deallocates all memory associated to a GValue.

[skip]

#### Parameters

value | the resource to free (or `NULL`). | [transfer full][nullable]

### gda_value_new_from_string ()

    GValue *
    gda_value_new_from_string (const gchar *as_string,
                               GType type);

Makes a new GValue of type `type` from its string representation.

For more information about the string format, see the `gda_value_set_from_string()` function. This function is typically used when reading configuration files or other non-user input that should be locale independent.

[skip]

#### Parameters

as_string | stringified representation of the value. |
type | the new value type. |

#### Returns

the newly created GValue or `NULL` if the string representation cannot be converted to the specified `type` .

Free-function: gda_value_free.

[transfer full]

### gda_value_set_from_string ()

    gboolean
    gda_value_set_from_string (GValue *value,
                               const gchar *as_string,
                               GType type);

Stores the value data from its string representation as `type` .

The accepted formats are:

- G_TYPE_BOOLEAN: a caseless comparison is made with "true" or "false"

- numerical types: C locale format (dot as a fraction separator)

- G_TYPE_DATE: see `gda_parse_iso8601_date()`

- GDA_TYPE_TIME: see `gda_parse_iso8601_time()`

- GDA_TYPE_TIMESTAMP: see `gda_parse_iso8601_timestamp()`

This function is typically used when reading configuration files or other non-user input that should be locale independent.

[skip]

#### Parameters

value | a GValue that will store `val` . |
as_string | the stringified representation of the value. |
type | the type of the value |

#### Returns

`TRUE` if the value has been converted to `type` from its string representation; it not means that the value is converted successfully, just that the transformation is available. `FALSE` otherwise.

### gda_value_set_from_value ()

    gboolean
    gda_value_set_from_value (GValue *value,
                              const GValue *from);

Sets the value of a GValue from another GValue. This is different from gda_value_copy, which creates a new GValue. gda_value_set_from_value, on the other hand, copies the contents of `copy` into `value` , which must already be allocated.

If values are incompatible (see `g_value_type_compatible` ) then `value` is set to a GDA_TYPE_NULL, and `FALSE` is returned.

[skip]

#### Parameters

value | a GValue. |
from | the value to copy from. |

#### Returns

`TRUE` if successful, `FALSE` otherwise.

### gda_value_stringify ()

    gchar *
    gda_value_stringify (const GValue *value);

Converts a GValue to its string representation which is a human readable value. Note that the returned string does not take into account the current locale of the user (on the contrary to the GdaDataHandler objects). Using this function should be limited to debugging and values serialization purposes.

Output is in the "C" locale for numbers, and dates are converted in a YYYY-MM-DD format.

#### Parameters

value | a GValue. |

#### Returns

a new string, or `NULL` if the conversion cannot be done. Free the value with a `g_free()` when you've finished using it.

[transfer full]

### gda_value_differ ()

    gint
    gda_value_differ (const GValue *value1,
                      const GValue *value2);

Tells if two values are equal or not, by comparing memory representations. Unlike `gda_value_compare()`, the returned value is boolean, and gives no idea about ordering.

The two values must be of the same type, with the exception that a value of any type can be compared to a GDA_TYPE_NULL value, specifically:

- if `value1` and `value2` are both GDA_TYPE_NULL values then the returned value is 0

- if `value1` is a GDA_TYPE_NULL value and `value2` is of another type then the returned value is 1

- if `value1` is of another type and `value2` is a GDA_TYPE_NULL value then the returned value is 1

- in all other cases, `value1` and `value2` must be of the same type and their values are compared

#### Parameters

value1 | a GValue to compare. |
value2 | the other GValue to be compared to `value1` . |

#### Returns

a non 0 value if `value1` and `value2` differ, and 0 if they are equal

### gda_value_compare ()

    gint
    gda_value_compare (const GValue *value1,
                       const GValue *value2);

Compares two values of the same type, with the exception that a value of any type can be compared to a GDA_TYPE_NULL value, specifically:

- if `value1` and `value2` are both GDA_TYPE_NULL values then the returned value is 0

- if `value1` is a GDA_TYPE_NULL value and `value2` is of another type then the returned value is -1

- if `value1` is of another type and `value2` is a GDA_TYPE_NULL value then the returned value is 1

- in all other cases, `value1` and `value2` must be of the same type and their values are compared

#### Parameters

value1 | a GValue to compare (not `NULL`) |
value2 | the other GValue to be compared to `value1` (not `NULL`) |

#### Returns

if both values have the same type, returns 0 if both contain the same value, an integer less than 0 if `value1` is less than `value2` or an integer greater than 0 if `value1` is greater than `value2` .

### gda_value_new_from_xml ()

    GValue *
    gda_value_new_from_xml (const xmlNodePtr node);

Creates a GValue from an XML representation of it. That XML node corresponds to the following string representation: <value type="gdatype">value</value>

For more information about the string format, see the `gda_value_set_from_string()` function. This function is typically used when reading configuration files or other non-user input that should be locale independent.

[skip]

#### Parameters

node | an XML node representing the value. |

#### Returns

the newly created GValue.

Free-function: gda_value_free.

[transfer full]

### gda_value_to_xml ()

    xmlNodePtr
    gda_value_to_xml (const GValue *value);

Serializes the given GValue to an XML node string.

[skip]

#### Parameters

value | a GValue. |

#### Returns

the XML node. Once not needed anymore, you should free it.

[transfer full]

### gda_value_reset_with_type ()

    void
    gda_value_reset_with_type (GValue *value,
                               GType type);

Resets the GValue and set a new type to GType.

[skip]

#### Parameters

value | the GValue to be reseted |
type | the GType to set to |

### gda_value_is_null ()

    gboolean
    gda_value_is_null (const GValue *value);

Tests if a given `value` is of type GDA_TYPE_NULL.

[skip]

#### Parameters

value | value to test. |

#### Returns

a boolean that says whether or not `value` is of type GDA_TYPE_NULL.

### gda_value_is_number ()

    gboolean
    gda_value_is_number (const GValue *value);

Gets whether the value stored in the given GValue is of numeric type or not.

[skip]

#### Parameters

value | a GValue. |

#### Returns

`TRUE` if a number, `FALSE` otherwise.

### gda_value_isa()

    #define             gda_value_isa(value, type)

### gda_value_new_binary ()

    GValue *
    gda_value_new_binary (const guchar *val,
                          glong size);

Makes a new GValue of type GDA_TYPE_BINARY with value `val` .

[skip]

#### Parameters

val | value to set for the new GValue. |
size | the size of the memory pool pointer to by `val` . |

#### Returns

the newly created GValue.

Free-function: gda_value_free.

[transfer full]

### gda_value_get_binary ()

    const GdaBinary *
    gda_value_get_binary (const GValue *value);

[skip]

#### Parameters

value | a GValue whose value we want to get. |

#### Returns

the value stored in `value` .

[transfer none]

### gda_value_set_binary ()

    void
    gda_value_set_binary (GValue *value,
                          const GdaBinary *binary);

Stores `val` into `value` .

[skip]

#### Parameters

value | a GValue that will store `val` . |
binary | a GdaBinary structure with the data and its size to be stored in `value` . |

### gda_value_take_binary ()

    void
    gda_value_take_binary (GValue *value,
                           GdaBinary *binary);

Stores `val` into `value` , but on the contrary to `gda_value_set_binary()`, the `binary` argument is not copied, but used as-is and it should be considered owned by `value` .

[skip]

#### Parameters

value | a GValue that will store `val` . |
binary | a GdaBinary structure with the data and its size to be stored in `value` . | [transfer full]

### gda_binary_copy ()

    gpointer
    gda_binary_copy (gpointer boxed);

Creates a new GdaBinary structure from an existing one.

#### Parameters

boxed | source to get a copy from. |

#### Returns

a newly allocated GdaBinary which contains a copy of information in `boxed` .

Free-function: gda_binary_free.

[transfer full]

### gda_binary_free ()

    void
    gda_binary_free (gpointer boxed);

Deallocates all memory associated to the given GdaBinary.

#### Parameters

boxed | GdaBinary to free. | [transfer full]

### gda_binary_to_string ()

    gchar *
    gda_binary_to_string (const GdaBinary *bin,
                          guint maxlen);

Converts all the non printable characters of bin->data into the "\xyz" representation where "xyz" is the octal representation of the byte, and the '\' (backslash) character is converted to "\". Printable characters (defined by `g_ascii_isprint()`) as well as newline character are not converted.

Note that the backslash and newline characters are considered as printable characters and will not be represented by the "\xyz" representation.

Use this function to get a representation as much readable by humans as possible of a binary chunk. Note that this function is internally called when transforming a binary value to a string for example when using `g_value_transform()` or `gda_value_stringify()`.

#### Parameters

bin | a correctly filled `GdaBinary` structure |
maxlen | a maximum len used to truncate, or `0` for no maximum length |

#### Returns

a new string from `bin` .

[transfer full]

### gda_string_to_binary ()

    GdaBinary *
    gda_string_to_binary (const gchar *str);

Performs the reverse of `gda_binary_to_string()` (note that for any "\xyz" succession of 4 characters where "xyz" represents a valid octal value, the resulting read value will be modulo 256).

I `str` is `NULL`, then an empty (i.e. where the `data` part is `NULL`) GdaBinary is created and returned.

#### Parameters

str | a string to convert, or `NULL`. | [nullable]

#### Returns

a new GdaBinary if no error were found in `str` , or `NULL` otherwise.

[transfer full]

### gda_value_new_blob ()

    GValue *
    gda_value_new_blob (const guchar *val,
                        glong size);

Makes a new GValue of type GDA_TYPE_BLOB with the data contained by `val` .

[skip]

#### Parameters

val | value to set for the new GValue. |
size | the size of the memory pool pointer to by `val` . |

#### Returns

the newly created GValue.

Free-function: gda_value_free.

[transfer full]

### gda_value_new_blob_from_file ()

    GValue *
    gda_value_new_blob_from_file (const gchar *filename);

Makes a new GValue of type GDA_TYPE_BLOB interfacing with the contents of the file named `filename`

[skip]

#### Parameters

filename | name of the file to manipulate |

#### Returns

the newly created GValue.

Free-function: gda_value_free.

[transfer full]

### gda_blob_copy ()

    gpointer
    gda_blob_copy (gpointer boxed);

Creates a new GdaBlob structure from an existing one.

#### Parameters

boxed | source to get a copy from. |

#### Returns

a newly allocated GdaBlob which contains a copy of information in `boxed` .

Free-function: gda_blob_free.

[transfer full]

### gda_blob_free ()

    void
    gda_blob_free (gpointer boxed);

Deallocates all memory associated to the given GdaBlob.

#### Parameters

boxed | GdaBlob to free. | [transfer full]

### gda_value_get_blob ()

    const GdaBlob *
    gda_value_get_blob (const GValue *value);

[skip]

#### Parameters

value | a GValue whose value we want to get. |

#### Returns

the value stored in `value` .

[transfer none]

### gda_value_set_blob ()

    void
    gda_value_set_blob (GValue *value,
                        const GdaBlob *blob);

Stores `val` into `value` .

[skip]

#### Parameters

value | a GValue that will store `val` . |
blob | a GdaBlob structure with the data and its size to be stored in `value` . |

### gda_value_take_blob ()

    void
    gda_value_take_blob (GValue *value,
                         GdaBlob *blob);

Stores `val` into `value` , but on the contrary to `gda_value_set_blob()`, the `blob` argument is not copied, but used as-is and it should be considered owned by `value` .

[skip]

#### Parameters

value | a GValue that will store `val` . |
blob | a GdaBlob structure with the data and its size to be stored in `value` . | [transfer full]

### gda_blob_set_op ()

    void
    gda_blob_set_op (GdaBlob *blob,
                     GdaBlobOp *op);

correctly assigns `op` to `blob`

#### Parameters

blob | a GdaBlob value |
op | a GdaBlobOp object, or `NULL`. | [nullable]

### gda_blob_to_string ()

    gchar *
    gda_blob_to_string (GdaBlob *blob,
                        guint maxlen);

Converts all the non printable characters of blob->data into the \xxx representation where xxx is the octal representation of the byte, and the '\' (backslash) character is converted to "\".

#### Parameters

blob | a correctly filled `GdaBlob` structure |
maxlen | a maximum len used to truncate, or 0 for no maximum length |

#### Returns

a new string from `blob` .

[transfer full]

### gda_geometricpoint_copy ()

    gpointer
    gda_geometricpoint_copy (gpointer boxed);

#### Returns

.

[transfer full]

### gda_geometricpoint_free ()

    void
    gda_geometricpoint_free (gpointer boxed);

### gda_value_get_geometric_point ()

    const GdaGeometricPoint *
    gda_value_get_geometric_point (const GValue *value);

[skip]

#### Parameters

value | a GValue whose value we want to get. |

#### Returns

the value stored in `value` .

[transfer none]

### gda_value_set_geometric_point ()

    void
    gda_value_set_geometric_point (GValue *value,
                                   const GdaGeometricPoint *val);

Stores `val` into `value` .

[skip]

#### Parameters

value | a GValue that will store `val` . |
val | value to be stored in `value` . |

### gda_numeric_new ()

    GdaNumeric *
    gda_numeric_new (void);

Creates a new GdaNumeric with defaults.

#### Returns

a new GdaNumeric.

[transfer full]

Since: 5.0.2

### gda_numeric_copy ()

    GdaNumeric *
    gda_numeric_copy (GdaNumeric *src);

Creates a new GdaNumeric structure from an existing one.

#### Parameters

src | source to get a copy from. |

#### Returns

a newly allocated GdaNumeric which contains a copy of information in `boxed` .

Free-function: gda_numeric_free.

[transfer full]

### gda_numeric_free ()

    void
    gda_numeric_free (GdaNumeric *numeric);

Deallocates all memory associated to the given `boxed`

#### Parameters

numeric | a GdaNumeric pointer. | [transfer full]

### gda_numeric_get_string ()

    gchar *
    gda_numeric_get_string (const GdaNumeric *numeric);

Get the string representation of `numeric` , in the C locale format (dot as a fraction separator).

#### Parameters

numeric | a GdaNumeric |

#### Returns

a new string representing the stored valued in `numeric` .

[transfer full][nullable]

Since: 5.0.2

### gda_numeric_get_double ()

    gdouble
    gda_numeric_get_double (const GdaNumeric *numeric);

#### Parameters

numeric | a GdaNumeric |

#### Returns

a gdouble representation of `numeric`

Since: 5.0.2

### gda_numeric_get_precision ()

    glong
    gda_numeric_get_precision (const GdaNumeric *numeric);

Gets the precision of a GdaNumeric.

#### Parameters

numeric | a GdaNumeric |

#### Returns

an integer with the precision of a GdaNumeric.

Since: 5.0.2

### gda_numeric_get_width ()

    glong
    gda_numeric_get_width (const GdaNumeric *numeric);

Gets the width of a GdaNumeric. (Not yet implemented).

#### Parameters

numeric | a GdaNumeric |

#### Returns

an integer with the width of a GdaNumeric. (Not jet implemented).

Since: 5.0.2

### gda_numeric_set_double ()

    void
    gda_numeric_set_double (GdaNumeric *numeric,
                            gdouble number);

Sets `numeric` using a gdouble represented by `number` .

#### Parameters

numeric | a GdaNumeric |
number | a gdouble |

Since: 5.0.2

### gda_numeric_set_from_string ()

    void
    gda_numeric_set_from_string (GdaNumeric *numeric,
                                 const gchar *str);

Sets `numeric` with a number represented by `str` , in the C locale format (dot as a fraction separator).

#### Parameters

numeric | a GdaNumeric |
str | a string representing a number, in the C locale format |

Since: 5.0.2

### gda_numeric_set_precision ()

    void
    gda_numeric_set_precision (GdaNumeric *numeric,
                               glong precision);

Sets the precision of a GdaNumeric.

#### Parameters

numeric | a GdaNumeric |
precision | a glong |

Since: 5.0.2

### gda_numeric_set_width ()

    void
    gda_numeric_set_width (GdaNumeric *numeric,
                           glong width);

Sets the width of a GdaNumeric. (Not yet implemented).

#### Parameters

numeric | a GdaNumeric |
width | a glong |

Since: 5.0.2

### gda_value_get_numeric ()

    const GdaNumeric *
    gda_value_get_numeric (const GValue *value);

[skip]

#### Parameters

value | a GValue whose value we want to get. |

#### Returns

the value stored in `value` .

[transfer none]

### gda_value_set_numeric ()

    void
    gda_value_set_numeric (GValue *value,
                           const GdaNumeric *val);

Stores `val` into `value` .

[skip]

#### Parameters

value | a GValue that will store `val` . |
val | value to be stored in `value` . |

### gda_time_copy ()

    gpointer
    gda_time_copy (gpointer boxed);

#### Returns

.

[transfer full]

### gda_time_free ()

    void
    gda_time_free (gpointer boxed);

### gda_time_valid ()

    gboolean
    gda_time_valid (const GdaTime *time);

#### Parameters

time | a GdaTime value to check if it is valid |

#### Returns

TRUE if GdaTime is valid; `FALSE` otherwise.

Since: 4.2

### gda_time_change_timezone ()

    void
    gda_time_change_timezone (GdaTime *time,
                              glong ntz);

Changes `time` 's timezone (for example to convert from GMT to another time zone). If `time` 's current timezone is unset (i.e. equal to `GDA_TIMEZONE_INVALID`), then this function simply sets `time` 's timezone attribute; Otherwise, it adds or removes hours, minutes or seconds to reflect the time in the new timezone.

Note: the resulting will always be a valid time.

#### Parameters

time | a valid GdaTime |
ntz | a new timezone to use, in seconds added to GMT |

Since: 5.2

### gda_value_get_time ()

    const GdaTime *
    gda_value_get_time (const GValue *value);

[skip]

#### Parameters

value | a GValue whose value we want to get. |

#### Returns

the value stored in `value` .

[transfer none]

### gda_value_set_time ()

    void
    gda_value_set_time (GValue *value,
                        const GdaTime *val);

Stores `val` into `value` .

[skip]

#### Parameters

value | a GValue that will store `val` . |
val | value to be stored in `value` . |

### gda_timestamp_copy ()

    gpointer
    gda_timestamp_copy (gpointer boxed);

#### Returns

.

[transfer full]

### gda_timestamp_free ()

    void
    gda_timestamp_free (gpointer boxed);

### gda_timestamp_valid ()

    gboolean
    gda_timestamp_valid (const GdaTimestamp *timestamp);

#### Parameters

timestamp | a GdaTimestamp value to check if it is valid |

#### Returns

TRUE if GdaTimestamp is valid; `FALSE` otherwise.

Since: 4.2

### gda_timestamp_change_timezone ()

    void
    gda_timestamp_change_timezone (GdaTimestamp *ts,
                                   glong ntz);

This function is similar to `gda_time_change_timezone()` but operates on time stamps.

Note: the resulting will always be a valid time.

#### Parameters

ts | a valid GdaTimestamp |
ntz | a new timezone to use, in seconds added to GMT |

Since: 5.2

### gda_value_get_timestamp ()

    const GdaTimestamp *
    gda_value_get_timestamp (const GValue *value);

[skip]

#### Parameters

value | a GValue whose value we want to get. |

#### Returns

the value stored in `value` .

[transfer none]

### gda_value_set_timestamp ()

    void
    gda_value_set_timestamp (GValue *value,
                             const GdaTimestamp *val);

Stores `val` into `value` .

[skip]

#### Parameters

value | a GValue that will store `val` . |
val | value to be stored in `value` . |

### gda_value_new_timestamp_from_timet ()

    GValue *
    gda_value_new_timestamp_from_timet (time_t val);

Makes a new GValue of type GDA_TYPE_TIMESTAMP with value `val` (of type time_t). The returned timestamp's value is relative to the current timezone (i.e. is localtime).

For example, to get a time stamp representing the current date and time, use:

`ts = gda_value_new_timestamp_from_timet (time (NULL));`

[skip]

#### Parameters

val | value to set for the new GValue. |

#### Returns

the newly created GValue, or `NULL` in case of error

Free-function: gda_value_free.

[transfer full]

### gda_value_get_short ()

    gshort
    gda_value_get_short (const GValue *value);

[skip]

#### Parameters

value | a GValue whose value we want to get. |

#### Returns

the value stored in `value` .

### gda_value_set_short ()

    void
    gda_value_set_short (GValue *value,
                         const gshort val);

Stores `val` into `value` .

[skip]

#### Parameters

value | a GValue that will store `val` . |
val | value to be stored in `value` . |

### gda_value_get_ushort ()

    gushort
    gda_value_get_ushort (const GValue *value);

[skip]

#### Parameters

value | a GValue whose value we want to get. |

#### Returns

the value stored in `value` .

### gda_value_set_ushort ()

    void
    gda_value_set_ushort (GValue *value,
                          const gushort val);

Stores `val` into `value` .

[skip]

#### Parameters

value | a GValue that will store `val` . |
val | value to be stored in `value` . |

## Types and Values

### enum GdaValueAttribute

#### Members

GDA_VALUE_ATTR_NONE |  |
GDA_VALUE_ATTR_IS_NULL |  |
GDA_VALUE_ATTR_CAN_BE_NULL |  |
GDA_VALUE_ATTR_IS_DEFAULT |  |
GDA_VALUE_ATTR_CAN_BE_DEFAULT |  |
GDA_VALUE_ATTR_IS_UNCHANGED |  |
GDA_VALUE_ATTR_ACTIONS_SHOWN |  |
GDA_VALUE_ATTR_DATA_NON_VALID |  |
GDA_VALUE_ATTR_HAS_VALUE_ORIG |  |
GDA_VALUE_ATTR_NO_MODIF |  |
GDA_VALUE_ATTR_UNUSED |  |

### GDA_TYPE_NULL

    #define             GDA_TYPE_NULL

### GDA_TYPE_DEFAULT

    #define             GDA_TYPE_DEFAULT

### GDA_TYPE_BINARY

    #define             GDA_TYPE_BINARY

### GDA_TYPE_BLOB

    #define             GDA_TYPE_BLOB

### GDA_TYPE_GEOMETRIC_POINT

    #define             GDA_TYPE_GEOMETRIC_POINT

### GDA_TYPE_NUMERIC

    #define             GDA_TYPE_NUMERIC

### GDA_TYPE_SHORT

    #define             GDA_TYPE_SHORT

### GDA_TYPE_USHORT

    #define             GDA_TYPE_USHORT

### GDA_TYPE_TIME

    #define             GDA_TYPE_TIME

### GDA_TYPE_TIMESTAMP

    #define             GDA_TYPE_TIMESTAMP

### GdaBinary

    typedef struct {
    	guchar *data;
    	glong   binary_length;
    } GdaBinary;

#### Members

guchar *`data`; | the actual data as an array. | [array]
glong `binary_length`; | length of `data` |

### GdaBlob

    typedef struct {
    	GdaBinary  data;
    	GdaBlobOp *op;
    } GdaBlob;

Represents some binary data, accessed through a GdaBlobOp object. `op` is generally set up by database providers when giving access to an existing BLOB in a database, but can be modified if needed using `gda_blob_set_op()`.

#### Members

GdaBinary `data`; | data buffer, as a GdaBinary |
GdaBlobOp *`op`; | a pointer to a GdaBlopOp, or `NULL`. | [allow-none]

### GdaGeometricPoint

    typedef struct {
    	gdouble x;
    	gdouble y;
    } GdaGeometricPoint;

### struct GdaNumeric

    struct GdaNumeric {
    	gchar*   GSEAL(number);
    	glong    GSEAL(precision);
    	glong    GSEAL(width);
    };

Holds numbers represented as strings.

This struct must be considered as opaque. Any access to its members must use its accessors added since version 5.0.2.

#### Members

### GdaTime

    typedef struct {
    	gushort hour;
    	gushort minute;
    	gushort second;
    	gulong  fraction;
    	glong   timezone;
    } GdaTime;

Represents a time information.

#### Members

gushort `hour`; | hour representation of the time, as a number between 0 and 23 |
gushort `minute`; | minute representation of the time, as a number between 0 and 59 |
gushort `second`; | second representation of the time, as a number between 0 and 59 |
gulong `fraction`; | fractionnal part of the seconds, in millionth' of second |
glong `timezone`; | number of seconds added to the GMT timezone |

### GdaTimestamp

    typedef struct {
    	gshort  year;
    	gushort month;
    	gushort day;
    	gushort hour;
    	gushort minute;
    	gushort second;
    	gulong  fraction;
    	glong   timezone;
    } GdaTimestamp;

Represents an instant (a time stamp)

#### Members

gshort `year`; | year representation of the time stamp |
gushort `month`; | month representation of the time stamp, as a number between 1 and 12 |
gushort `day`; | day representation of the time stamp, as a number between 1 and 31 |
gushort `hour`; | hour representation of the time stamp, as a number between 0 and 23 |
gushort `minute`; | minute representation of the time stamp, as a number between 0 and 59 |
gushort `second`; | second representation of the time stamp, as a number between 0 and 59 |
gulong `fraction`; | fractionnal part of the seconds, in millionth' of second |
glong `timezone`; | number of seconds added to the GMT timezone |

## See Also

GValue and GdaBlobOp