SincpacC3D
General Information
Command Summary
Regular Expressions
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SincpacC3D
General Information
Command Summary
Regular Expressions |
The option for "Use Regular Expression" is very powerful. With a normal search, the Find string must exactly match the text in the Raw Description. However, when "Use Regular Expression" is checked, both the Find and Replace strings are treated as Regular Expressions.
There are many options in Regular Expressions. For the most part, the characters in a Regular Expression are literal characters to match - the letter "a" matches the letter "a", and so forth. However, some characters in Regular Expressions have special meanings.
Some of the most-useful features of regular expressions are described here. However, Regular Expressions are a rather rich subject, and more information on them can be found by searching the web.
Character Escapes
Character Escapes are indicated using the Backslash ("\"). A Character Escape is simply a way of using normal letters to specify special characters. Some of the most-useful Character Escapes are in the table below:
Character Escape |
Description |
\t |
Tab character. |
\040 |
ASCII code in octal. |
\x20 |
ASCII code in hexadecimal |
\u0020 |
Matches a Unicode character string. |
\\ |
Matches a literal backslash. |
Character Classes
Character Classes indicate a set of characters. A Character Class will match any of the characters in its component set.
Character Class |
Description |
. |
Matches any character except \n (newline). |
[aeiou] |
Matches any single character in the specified group. The example to the left would match any of the vowels (a, e, i, o, or u). A hyphen may also be used to specify a contiguous range of characters, e.g. [a-z] specifies all lowercase letters from a to z. |
[^aeiou] |
Matches any single character EXCEPT for those in the specified group. The example to the left would match any character EXCEPT for one of the vowels (a, e, i, o, or u). Hyphens may also be used to specify a contiguous range of characters. |
^ |
Matches the start of the string the pattern is being applied to. |
$ |
Matches the end of the string the pattern is being applied to. |
\w |
Matches any word character. The same as [a-zA-Z_0-9]. |
\W |
Matches any character that is NOT a word character. The same as [^a-zA-Z_0-9]. |
\d |
Matches any numerical digit. The same as [0-9]. |
\D |
Matches any character that is NOT a numerical digit. The same as [^0-9]. |
\s |
Matches any whitespace character (tabs, spaces, etc.). |
\S |
Matches any non-whitespace character. |
\b |
A word boundary, i.e. the transition between \w and \W characters. (May also indicate a backspace in certain cases.) |
Quantifiers
Quantifiers indicate how many occurrences of the preceding character can be matched. For new-comers to Regular Expressions, one of their most-confusing aspects is that the asterisk (*) is a Quantifier in a Regular Expression, and not a wildcard. The difference can be seen in the Examples later in this page.
Some of the most-useful Character Escapes are in the table below:
Quantifier |
Description |
? |
Matches either 0 or 1 occurrences of the preceding character. Basically, makes the preceding character optional in the match. |
+ |
Matches 1 or more occurrences of the preceding character. Will match as many characters as possible. |
+? |
Matches 1 or more occurrences of the preceding character. Will match as few characters as possible. |
* |
Matches 0 or more occurrences of the preceding character. Will match as many characters as possible. |
*? |
Matches 0 or more occurrences of the preceding character. Will match as few characters as possible. |
These quantifiers are processed from left to right. This is usually only important when using grouping characters. See the sample regular expressions at the end of this page for some examples of this.
Grouping and Back References
It is also possible to create a group out of a portion of a Regular Expression, and then refer to that group later. A Group is created by using parentheses to indicate the limits of the group. Multiple groups may be declared in the same Regular Expression.
These Groups may then be referenced in the replacement string by using $1 to refer to the first one, $2 to refer to the second, $3 for the third, etc., through $9. See the end of the Sample Regular Expressions for some examples of how grouping works.
Sample Regular Expressions
Find String |
Replace String |
Sample Input and Output |
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ABC |
XYZ |
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ABC? |
XYZ |
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ABC+ |
XYZ |
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ABC* |
XYZ |
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ABC.+ |
XYZ |
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ABC.* |
XYZ |
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^ABC |
XYZ |
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ABC$ |
XYZ |
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(.+)\W+(.+) |
$2 $1 |
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(.+?)\W+(.+) |
$2 $1 |
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