Streams Package Exception Classes
Class
RWExternalStreamException is the base class for all exception classes in the Streams package. It returns an error message that can be accessed through the inherited member function
why(), and an error code that can be accessed through the member function
errorCode(). The
errorCode() function returns a value of type
ErrorCode, which is an enumeration. Error codes
0 through
11 have the following meaning:
ok | everything is fine |
flush | error while flushing the stream |
write | error while writing to the stream |
read | error while reading an RWByte, char, wchar_t, or RWUChar |
get | error while reading a datatype |
internalOstream | the internal ostream object is in a fail or bad state |
internalIstream | the internal istream object is in a fail or bad state |
featureNotSupported | reports a feature not currently supported due to compiler limitation |
outOfMemory | the last memory allocation request failed |
invalidParameter | one of the parameters has been assigned an invalid value |
invalidUnicodeEncoding | a sequence of RWUChar does not represent a valid sequence of UTF-16 character(s) |
invalidUTF8Encoding | a sequence of bytes is not formatted according to UTF-8 |
Error codes 12 through 499 are not currently assigned, but are reserved by Rogue Wave for future use. If you want to return your own error code, use a value greater or equal to 500.
Class
RWIncompleteStreamOperation is thrown to report operations that have been partially fulfilled. For instance, an output stream function writing an array of elements might write several elements before encountering a fatal error. In this case, the function throws an instance of class
RWIncompleteStreamOperation, which can be queried using the member function
elementsProcessed() to get the number of elements successfully written prior to failure.
The following code shows how to handle stream exceptions:
try {
// some stream operation
}
catch(const RWIncompleteStreamOperation& e) {
cout << e.why() << endl;
cout << "the number of element(s) successfully processed is: "
<< e.elementsProcessed() << endl;
if (e.errorCode() == RWExternalStreamException::outOfMemory)
cout << “we ran out of memory” << endl;
}
catch(const RWExternalStreamException& e) {
cout << e.why() << endl;
if (e.errorCode() == RWExternalStreamException::outOfMemory)
cout << “we ran out of memory” << endl;
}
