Rss C Reference Documentation

Rss

Current Version: 9.5.0.73

Represents an RSS document or sub-part of a document such as a channel, image, or item. The RSS API allows one to download, create and modify RSS documents.

Create/Dispose

HCkRss instance = CkRss_Create();
// ...
CkRss_Dispose(instance);
HCkRss CkRss_Create(void);

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

void CkRss_Dispose(HCkRss handle);

Objects created by calling CkRss_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 CkRss_Dispose.

Callback Functions

Callback Functions introduced in Chilkat v9.5.0.56
void CkRss_setAbortCheck(HCkRss cHandle, BOOL (*fnAbortCheck)(void));

Provides the opportunity for a method call to be aborted. If TRUE is returned, the operation in progress is aborted. Return FALSE to allow the current method call to continue. This callback function is called periodically based on the value of the HeartbeatMs property. (If HeartbeatMs is 0, then no callbacks are made.) As an example, to make 5 AbortCheck callbacks per second, set the HeartbeatMs property equal to 200.

void CkRss_setPercentDone(HCkRss cHandle, BOOL (*fnPercentDone)(int pctDone));

Provides the percentage completed for any method that involves network communications or time-consuming processing (assuming it is a method where a percentage completion can be measured). This callback is only called when it is possible to know a percentage completion, and when it makes sense to express the operation as a percentage completed. The pctDone argument will have a value from 1 to 100. For methods that complete very quickly, the number of PercentDone callbacks will vary, but the final callback should have a value of 100. For long running operations, no more than one callback per percentage point will occur (for example: 1, 2, 3, ... 98, 99, 100).

This callback counts as an AbortCheck callback, and takes the place of the AbortCheck event when it fires.

The return value indicates whether the method call should be aborted, or whether it should proceed. Return TRUE to abort, and FALSE to proceed.

void CkRss_setProgressInfo(HCkRss cHandle, void (*fnProgressInfo)(const char *name, const char *value));

This is a general callback that provides name/value information about what is happening at certain points during a method call. To see the information provided in ProgressInfo callbacks, if any, write code to handle this event and log the name/value pairs. Most are self-explanatory.

void CkRss_setTaskCompleted(HCkRss cHandle, void (*fnTaskCompleted)(HCkTask hTask));

Called in the background thread when an asynchronous task completes. (Note: When an async method is running, all callbacks are in the background thread.)

Properties

DebugLogFilePath
void CkRss_getDebugLogFilePath(HCkRss cHandle, HCkString retval);
void CkRss_putDebugLogFilePath(HCkRss cHandle, const char *newVal);
const char *CkRss_debugLogFilePath(HCkRss cHandle);

If set to a file path, causes each Chilkat method or property call to automatically append it's LastErrorText to the specified log file. The information is appended such that if a hang or crash occurs, it is possible to see the context in which the problem occurred, as well as a history of all Chilkat calls up to the point of the problem. The VerboseLogging property can be set to provide more detailed information.

This property is typically used for debugging the rare cases where a Chilkat method call hangs or generates an exception that halts program execution (i.e. crashes). A hang or crash should generally never happen. The typical causes of a hang are:

  1. a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
  2. the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
  3. there is an internal problem (bug) in the Chilkat code that causes the hang.

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LastErrorHtml
void CkRss_getLastErrorHtml(HCkRss cHandle, HCkString retval);
const char *CkRss_lastErrorHtml(HCkRss cHandle);

Provides information in HTML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorText
void CkRss_getLastErrorText(HCkRss cHandle, HCkString retval);
const char *CkRss_lastErrorText(HCkRss cHandle);

Provides information in plain-text format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorXml
void CkRss_getLastErrorXml(HCkRss cHandle, HCkString retval);
const char *CkRss_lastErrorXml(HCkRss cHandle);

Provides information in XML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastMethodSuccess
BOOL CkRss_getLastMethodSuccess(HCkRss cHandle);
void CkRss_putLastMethodSuccess(HCkRss 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.

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NumChannels
int CkRss_getNumChannels(HCkRss cHandle);

The number of channels in the RSS document.

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NumItems
int CkRss_getNumItems(HCkRss cHandle);

The number of items in the channel.

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Utf8
BOOL CkRss_getUtf8(HCkRss cHandle);
void CkRss_putUtf8(HCkRss 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.

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VerboseLogging
BOOL CkRss_getVerboseLogging(HCkRss cHandle);
void CkRss_putVerboseLogging(HCkRss cHandle, BOOL newVal);

If set to TRUE, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is FALSE. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

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Version
void CkRss_getVersion(HCkRss cHandle, HCkString retval);
const char *CkRss_version(HCkRss cHandle);

Version of the component/library, such as "9.5.0.63"

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Methods

AddNewChannel
HCkRss CkRss_AddNewChannel(HCkRss cHandle);

Adds a new channel to the RSS document. Returns the Rss object representing the Channel which can then be edited.

Returns NULL on failure

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AddNewImage
HCkRss CkRss_AddNewImage(HCkRss cHandle);

Adds a new image to the RSS document. Returns the Rss object representing the image, which can then be edited.

Returns NULL on failure

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AddNewItem
HCkRss CkRss_AddNewItem(HCkRss cHandle);

Adds a new Item to an Rss channel. Returns the Rss object representing the item which can then be edited.

Returns NULL on failure

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DownloadRss
BOOL CkRss_DownloadRss(HCkRss cHandle, const char *url);

Downloads an RSS document from the Internet and populates the Rss object with the contents.

Returns TRUE for success, FALSE for failure.

More Information and Examples
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DownloadRssAsync (1)
HCkTask CkRss_DownloadRssAsync(HCkRss cHandle, const char *url);

Creates an asynchronous task to call the DownloadRss method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Returns NULL on failure

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GetAttr
BOOL CkRss_GetAttr(HCkRss cHandle, const char *tag, const char *attrName, HCkString outStr);
const char *CkRss_getAttr(HCkRss cHandle, const char *tag, const char *attrName);

Returns the value of a sub-element attribute. For example, to get the value of the "isPermaLink" attribute of the "guid" sub-element, call item.GetAttr("guid","isPermaLink").

Returns TRUE for success, FALSE for failure.

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GetChannel
HCkRss CkRss_GetChannel(HCkRss cHandle, int index);

Returns the Nth channel of an RSS document. Usually there is only 1 channel per document, so the index argument should be set to 0.

Returns NULL on failure

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GetCount
int CkRss_GetCount(HCkRss cHandle, const char *tag);

Return the number of sub-elements with a specific tag.

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GetDate
BOOL CkRss_GetDate(HCkRss cHandle, const char *tag, SYSTEMTIME *outSysTime);
This method is deprecated. It will be removed in a future version.

Return the value of a sub-element in date/time format.

Returns TRUE for success, FALSE for failure.

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GetDateStr
BOOL CkRss_GetDateStr(HCkRss cHandle, const char *tag, HCkString outStr);
const char *CkRss_getDateStr(HCkRss cHandle, const char *tag);

The same as GetDate, except the date/time is returned in RFC822 string format.

Returns TRUE for success, FALSE for failure.

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GetImage
HCkRss CkRss_GetImage(HCkRss cHandle);

Return the image associated with the channel.

Returns NULL on failure

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GetInt
int CkRss_GetInt(HCkRss cHandle, const char *tag);

Return the value of a numeric sub-element as an integer.

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GetItem
HCkRss CkRss_GetItem(HCkRss cHandle, int index);

Return the Nth item of a channel as an RSS object.

Returns NULL on failure

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GetString
BOOL CkRss_GetString(HCkRss cHandle, const char *tag, HCkString outStr);
const char *CkRss_getString(HCkRss cHandle, const char *tag);

Return the value of an sub-element as a string.

Returns TRUE for success, FALSE for failure.

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LoadRssFile
BOOL CkRss_LoadRssFile(HCkRss cHandle, const char *filePath);

Load an RSS document from a file.

Returns TRUE for success, FALSE for failure.

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LoadRssString
BOOL CkRss_LoadRssString(HCkRss cHandle, const char *rssString);

Loads an RSS feed document from an in-memory string.

Returns TRUE for success, FALSE for failure.

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MGetAttr
BOOL CkRss_MGetAttr(HCkRss cHandle, const char *tag, int index, const char *attrName, HCkString outStr);
const char *CkRss_mGetAttr(HCkRss cHandle, const char *tag, int index, const char *attrName);

Get an attribute value for the Nth sub-element having a specific tag. As an example, an RSS item may have several "category" sub-elements. To get the value of the "domain" attribute for the 3rd category, call MGetAttr("category",2,"domain").

Returns TRUE for success, FALSE for failure.

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MGetString
BOOL CkRss_MGetString(HCkRss cHandle, const char *tag, int index, HCkString outStr);
const char *CkRss_mGetString(HCkRss cHandle, const char *tag, int index);

Get the value of the Nth occurrence of a sub-element. Indexing begins at 0.

Returns TRUE for success, FALSE for failure.

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MSetAttr
BOOL CkRss_MSetAttr(HCkRss cHandle, const char *tag, int idx, const char *attrName, const char *value);

Set an attribute on the Nth occurrence of a sub-element.

Returns TRUE for success, FALSE for failure.

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MSetString
BOOL CkRss_MSetString(HCkRss cHandle, const char *tag, int idx, const char *value);

Set the value of the Nth occurrence of a sub-element. Indexing begins at 0.

Returns TRUE for success, FALSE for failure.

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NewRss
void CkRss_NewRss(HCkRss cHandle);

Clears the RSS document.

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Remove
void CkRss_Remove(HCkRss cHandle, const char *tag);

Removes a sub-element from the RSS document.

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SaveLastError
BOOL CkRss_SaveLastError(HCkRss cHandle, const char *path);

Saves the last-error information (the contents of LastErrorXml) to an XML formatted file.

Returns TRUE for success, FALSE for failure.

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SetAttr
void CkRss_SetAttr(HCkRss cHandle, const char *tag, const char *attrName, const char *value);

Sets the value of a sub-element attribute.

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SetDate
void CkRss_SetDate(HCkRss cHandle, const char *tag, SYSTEMTIME * dateTime);
This method is deprecated. It will be removed in a future version.

Sets the value of a date/time sub-element.

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SetDateNow
void CkRss_SetDateNow(HCkRss cHandle, const char *tag);

Sets the value of a date/time sub-element to the current system date/time.

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SetDateStr
void CkRss_SetDateStr(HCkRss cHandle, const char *tag, const char *dateTimeStr);

The same as SetDate, except the date/time is passed as an RFC822 string.

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SetInt
void CkRss_SetInt(HCkRss cHandle, const char *tag, int value);

Sets the value of an integer sub-element.

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SetString
void CkRss_SetString(HCkRss cHandle, const char *tag, const char *value);

Sets the value of a sub-element.

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ToXmlString
BOOL CkRss_ToXmlString(HCkRss cHandle, HCkString outStr);
const char *CkRss_toXmlString(HCkRss cHandle);

Returns the RSS document as an XML string.

Returns TRUE for success, FALSE for failure.

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