REX Replacement Strings

NOTE: Any expression may be searched for in conjunction with a replace operation but the replacement string will always be of fixed size.

An expression will be defined one way when given to REX to search for; it will be defined another way when used with the `-r' or `-R' Replace options as the replacement string. The characters ``?#{}+'' have entirely different meanings when used as part of the syntax of a replacement string, than when used as part of the syntax of expressions or repetition operators.

Replacement syntax is different from expression syntax, and is limited to the following delineated rules.

• Replacement strings may just be a literal string or they may include the ``ditto'' character ``?''. The ditto character will copy the character in the position specified in the replace string from the same position in the located expression.

• A decimal digit placed within curly braces ( eg: {5} ) will place that character of the located expression to the output.

• A plus character ``+'' will place an incrementing decimal number to the output. One purpose of this operator is to number lines.

• A ``#'' in the replace string will cause the character in that position to be printed in hexadecimal form.

• To replace with the literal characters ``?#{}+'' precede them with the escapement character ``\''.

• Any character in the replace string may be represented by the hexadecimal value of that character using the following syntax: \Xdd where ``dd'' is the hexadecimal value.