(No version information available, might be only in CVS)
unicode_set_subst_char — Set the substitution character for string conversion errors
When converting a string from or to unicode, an invalid or unconvertable character may be encountered. When the conversion error mode is set to U_CONV_ERROR_SUBST, the character that caused the error is substituted by a character set by this function. The default substitution character is ?.
The substitution character to use.
如果成功则返回 TRUE，失败则返回 FALSE。
Emits a E_WARNING level error if character is invalid.
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