Variables 3 RASQAL Library
Variables Variable with names and literal value.

## Synopsis

                rasqal_variable;
    rasqal_variable* rasqal_new_variable        (rasqal_query *rq,
                                                 unsigned char *name,
                                                 rasqal_literal *value);
    rasqal_variable* rasqal_new_variable_typed  (rasqal_query *rq,
                                                 rasqal_variable_type type,
                                                 unsigned char *name,
                                                 rasqal_literal *value);
    void        rasqal_free_variable            (rasqal_variable *v);
    void        rasqal_variable_print           (rasqal_variable *v,
                                                 FILE *fh);
    void        rasqal_variable_set_value       (rasqal_variable *v,
                                                 rasqal_literal *l);
    enum        rasqal_variable_type;

## Description

A class to hold a variable with optional name and a rasqal_literal value. The name is not required for SPARQL anonymous variables, when constructed with `rasqal_new_variable_typed()` and type RASQAL_VARIABLE_TYPE_ANONYMOUS.

## Details

### rasqal_variable

    typedef struct {
      const unsigned char *name;
      rasqal_literal* value;
      int offset;
      rasqal_variable_type type;
    } rasqal_variable;

Binding between a variable name and a value.

Includes internal field offset for recording the offset into the (internal) rasqal_query variables array.

const unsigned char *name;

  Variable name.

rasqal_literal *value;

  Variable value or NULL if unbound.

int offset;

  Internal.

rasqal_variable_type type;

  Variable type.

rasqal_variable

### rasqal_new_variable ()

    rasqal_variable* rasqal_new_variable        (rasqal_query *rq,
                                                 unsigned char *name,
                                                 rasqal_literal *value);

Constructor - Create a new Rasqal normal variable.

The variable must be associated with a query, since variable names are only significant with a single query.

This creates a regular variable that can be returned of type RASQAL_VARIABLE_TYPE_NORMAL. Use rasqal_new_variable_typed to create other variables.

The name and value become owned by the rasqal_variable structure

rq :

  rasqal_query to associate the variable with

name :

  variable name

value :

  variable rasqal_literal value (or NULL)

Returns :

  a new rasqal_variable or NULL on failure.

rasqal_new_variable

### rasqal_new_variable_typed ()

    rasqal_variable* rasqal_new_variable_typed  (rasqal_query *rq,
                                                 rasqal_variable_type type,
                                                 unsigned char *name,
                                                 rasqal_literal *value);

Constructor - Create a new typed Rasqal variable.

The variable must be associated with a query, since variable names are only significant with a single query.

The name and value become owned by the rasqal_variable structure

rq :

  rasqal_query to associate the variable with

type :

  variable type defined by enumeration rasqal_variable_type

name :

  variable name

value :

  variable rasqal_literal value (or NULL)

Returns :

  a new rasqal_variable or NULL on failure.

rasqal_new_variable_typed

### rasqal_free_variable ()

    void        rasqal_free_variable            (rasqal_variable *v);

Destructor - Destroy a Rasqal variable object.

v :

  rasqal_variable object

rasqal_free_variable

### rasqal_variable_print ()

    void        rasqal_variable_print           (rasqal_variable *v,
                                                 FILE *fh);

Print a Rasqal variable in a debug format.

The print debug format may change in any release.

v :

  the rasqal_variable object

fh :

  the FILE* handle to print to

rasqal_variable_print

### rasqal_variable_set_value ()

    void        rasqal_variable_set_value       (rasqal_variable *v,
                                                 rasqal_literal *l);

Set the value of a Rasqal variable.

The variable value is an input parameter and is copied in, not shared. If the variable value is NULL, any existing value is deleted.

v :

  the rasqal_variable object

l :

  the rasqal_literal value to set (or NULL)

rasqal_variable_set_value

### enum rasqal_variable_type

    typedef enum {
      RASQAL_VARIABLE_TYPE_UNKNOWN   = 0,
      RASQAL_VARIABLE_TYPE_NORMAL    = 1,
      RASQAL_VARIABLE_TYPE_ANONYMOUS = 2
    } rasqal_variable_type;

Rasqal variable types.

ANONYMOUS can be used in queries but cannot be returned in a result.

`RASQAL_VARIABLE_TYPE_UNKNOWN`

  Internal.

`RASQAL_VARIABLE_TYPE_NORMAL`

  The regular variable type.

`RASQAL_VARIABLE_TYPE_ANONYMOUS`

  Anonymous variable type.

rasqal_variable_type