A conversion simply maps characters from a source encoding to a target encoding. Normally this is a straightforward process of replacing all the code point values for characters in the source encoding with the code point values for those characters in the target encoding. However, errors can occur in this process. For example, the character being converted may not have a representation in the target encoding, or the code units in the source string may be impossible to interpret as a code point value in the source encoding. When errors such as these occur, the converter can respond in several ways:

For both RWUToUnicodeConverter and RWUFromUnicodeConverter, the default error-handling response is to substitute for the offending character. RWUToUnicodeConverter uses U+FFFD as its substitution sequence. RWUFromUnicodeConverter uses a substitution sequence appropriate for the target encoding. For example, the substitution sequence for most ASCII-based encodings is 0x1a. You can change the default substitution sequence for a conversion from Unicode by calling RWUFromUnicodeConverter::setSubstitutionSequence().

To change a converter’s error-handling behavior, call method RWUToUnicodeConverter::setErrorResponse() or method RWUFromUnicodeConverter::setErrorResponse(). Each of these methods accepts an enum value. The set of available enum values depends on the direction of the converter. The function RWUToUncodeConverter::setErrorResponse() accepts the following enum values:

The function RWUFromUnicodeConverter::setErrorResponse() provides a similar set of error-handling tactics, but supports a wider variety of escaping options to facilitate working with different target encodings: