I can attest that K&R is still relevant and it is an excellent book; I have a hardcopy. However, the case is different: C is standardized, Perl is not. The C language, save unofficial vendor extensions, remained the same for a good ten years or so (from C89 to C99). No new keywords, same semantics. Even the standard library stayed the same. Also, most common C compilers still fail to support the full C99 standard, which means most C code is still C89. Reading perl58\d?delta, as linked by ysth, indicates that Perl has indeed changed in seven years.