Hashtable C Reference Documentation

Hashtable

Represents a collection of key/value pairs that are stored in a hash table.

Note: This class was added in Chilkat v9.5.0.51

Create/Dispose

HCkHashtable CkHashtable_Create(void);

Creates an instance of the HCkHashtable object and returns a handle (i.e. a "void *" pointer). The handle is passed in the 1st argument for the functions listed on this page.

void CkHashtable_Dispose(HCkHashtable handle);

Objects created by calling CkHashtable_Create must be freed by calling this method. A memory leak occurs if a handle is not disposed by calling this function. Also, any handle returned by a Chilkat "C" function must also be freed by the application by calling the appropriate Dispose method, such as CkHashtable_Dispose.

Properties

BOOL CkHashtable_getLastMethodSuccess(HCkHashtable cHandle);

void CkHashtable_putLastMethodSuccess(HCkHashtable cHandle, BOOL newVal);

Introduced in version 9.5.0.52

Indicate whether the last method call succeeded or failed. A value of TRUE indicates success, a value of FALSE indicates failure. This property is automatically set for method calls. It is not modified by property accesses. The property is automatically set to indicate success for the following types of method calls:

  • Any method that returns a string.
  • Any method returning a Chilkat object, binary bytes, or a date/time.
  • Any method returning a standard boolean status value where success = TRUE and failure = FALSE.
  • Any method returning an integer where failure is defined by a return value less than zero.

Note: Methods that do not fit the above requirements will always set this property equal to TRUE. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.

BOOL CkHashtable_getUtf8(HCkHashtable cHandle);

void CkHashtable_putUtf8(HCkHashtable cHandle, BOOL newVal);

When set to TRUE, all "const char *" arguments are interpreted as utf-8 strings. If set to FALSE (the default), then "const char *" arguments are interpreted as ANSI strings. Also, when set to TRUE, and Chilkat method returning a "const char *" is returning the utf-8 representation. If set to FALSE, all "const char *" return values are ANSI strings.

Methods

BOOL CkHashtable_AddFromXmlSb(HCkHashtable cHandle, HCkStringBuilder sbXml);

Introduced in version 9.5.0.64

Adds to the hash table from XML previously created by calling ToXmlSb.

Returns TRUE for success, FALSE for failure.

Serialize / Deserialize Hashtable to/from XML

BOOL CkHashtable_AddInt(HCkHashtable cHandle, const char *key, int value);

Introduced in version 9.5.0.51

Adds or replaces an entry with the given key and integer value to the hash table. Returns TRUE if a new hash entry was added or replaced. Returns FALSE if an out-of-memory condition occurred.

Returns TRUE for success, FALSE for failure.

BOOL CkHashtable_AddQueryParams(HCkHashtable cHandle, const char *queryParams);

Introduced in version 9.5.0.62

Adds URL query parameters into the hashtable. The queryParams has the form: "field1=value1&field2=value2&field3=value3...". It is assumed that the values are URL encoded, and this method automatically URL decodes the values prior to inserting into the hashtable.

Returns TRUE for success, FALSE for failure.

BOOL CkHashtable_AddStr(HCkHashtable cHandle, const char *key, const char *value);

Introduced in version 9.5.0.51

Adds or replaces an entry with the given key and string value to the hash table. Returns TRUE if a new hash entry was added or replaced. Returns FALSE if an out-of-memory condition occurred.

Returns TRUE for success, FALSE for failure.

void CkHashtable_Clear(HCkHashtable cHandle);

Introduced in version 9.5.0.51

Removes all elements from the Hashtable.

BOOL CkHashtable_ClearWithNewCapacity(HCkHashtable cHandle, int capacity);

Introduced in version 9.5.0.51

Removes all elements from the Hashtable and re-sizes with the specified capacity.

The capacity is the number of buckets in the hash table. In the case of a "hash collision", a single bucket stores multiple entries, which must be searched sequentially. One rule of thumb is to set the capacity to twice the number of expected items to be hashed. It's also preferable to set the capacity to a prime number. (The 1st 10,000 prime numbers are listed here: https://primes.utm.edu/lists/small/10000.txt )

The initial default capacity of the hash table is 521.

Returns TRUE for success, FALSE for failure.

BOOL CkHashtable_Contains(HCkHashtable cHandle, const char *key);

Introduced in version 9.5.0.51

Determines if a given key is contained within the hash table. Returns TRUE if the key exists, otherwise returns FALSE.

BOOL CkHashtable_ContainsIntKey(HCkHashtable cHandle, int key);

Introduced in version 9.5.0.64

Determines if a given key is contained within the hash table. Returns TRUE if the key exists, otherwise returns FALSE.

BOOL CkHashtable_GetKeys(HCkHashtable cHandle, HCkStringTable strTable);

Introduced in version 9.5.0.62

Appends the complete set of hashtable key strings to strTable.

Returns TRUE for success, FALSE for failure.

Serialize / Deserialize Hashtable to/from XML

int CkHashtable_LookupInt(HCkHashtable cHandle, const char *key);

Introduced in version 9.5.0.51

Returns the integer value associated with the specified key. If the key is not in the hash table, the return value is 0.

BOOL CkHashtable_LookupStr(HCkHashtable cHandle, const char *key, HCkString outStr);

const char *CkHashtable_lookupStr(HCkHashtable cHandle, const char *key);

Introduced in version 9.5.0.51

Returns the string value associated with the specified key.

Returns TRUE for success, FALSE for failure.

BOOL CkHashtable_Remove(HCkHashtable cHandle, const char *key);

Introduced in version 9.5.0.51

Removes the entry with the specified key from the hash table. Returns TRUE if the key existed and was removed. Returns FALSE if the key did not already exist.

BOOL CkHashtable_ToXmlSb(HCkHashtable cHandle, HCkStringBuilder sbXml);

Introduced in version 9.5.0.64

Serializes the hash table to XML format. The XML is appended to sbXml.

Returns TRUE for success, FALSE for failure.

Serialize / Deserialize Hashtable to/from XML