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codice:
Tabella 11-1. Escaped characters

sequence meaning 
\n linefeed (LF or 0x0A (10) in ASCII) 
\r carriage return (CR or 0x0D (13) in ASCII) 
\t horizontal tab (HT or 0x09 (9) in ASCII) 
\\ backslash 
\$ dollar sign 
\" double-quote 
\[0-7]{1,3} the sequence of characters matching the regular expression is a character in octal notation  
\x[0-9A-Fa-f]{1,2} the sequence of characters matching the regular expression is a character in hexadecimal notation
evidentemente utilizzi male il carattere di escape cioe' il backslash \ , viene interpretato male. Prova ad usare lo slash oppure il doppio backslash.