ldap_first_attributeW function (winldap.h)

Article
02/09/2023

For a given directory entry, the ldap_first_attribute function returns the first attribute.

Syntax

WINLDAPAPI PWCHAR LDAPAPI ldap_first_attributeW(
  [in]  LDAP        *ld,
  [in]  LDAPMessage *entry,
  [out] BerElement  **ptr
);

Parameters

[in] ld

The session handle.

[in] entry

The entry whose attributes are to be stepped through, as returned by ldap_first_entry or ldap_next_entry.

[out] ptr

The address of a pointer used internally to track the current position in the entry.

Return value

A pointer to a null-terminated string. If the function succeeds, it returns a pointer to an allocated buffer that contains the current attribute name. When there are no more attributes to step through, it returns NULL. The session error parameter in the LDAP data structure is set to 0 in either case.

If the function fails, it returns NULL and sets the session error parameter in the LDAP data structure to the LDAP error code.

Remarks

Use ldap_first_attribute in conjunction with ldap_next_attribute to step through the list of attribute types returned with an entry. You can then pass these attribute names in a call to ldap_get_values to retrieve their associated values.

A call to ldap_first_attribute allocates, and returns through the ptr parameter, a pointer to a BerElement structure. Pass this pointer to ldap_next_attribute to track the current position in the list of attributes. When you have finished stepping through a list of attributes and ptr is non-NULL, free the pointer by calling ber_free( ptr, 0 ). Be aware that you must pass the second parameter as 0 (zero) in this call.

Both ldap_first_attribute and ldap_next_attribute return a pointer to an allocated buffer containing the current attribute name. Free this buffer, when no longer required, by calling ldap_memfree. Because this buffer is overwritten on the next call to either ldap_first_attribute or
ldap_next_attribute, the user should make a copy of the attribute name if it must be preserved for processing.

Note

The winldap.h header defines ldap_first_attribute as an alias which automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.

Requirements

Requirement	Value
Minimum supported client	Windows Vista
Minimum supported server	Windows Server 2008
Target Platform	Windows
Header	winldap.h
Library	Wldap32.lib
DLL	Wldap32.dll