Q. What are examples of regular expressions?

• strings surrounded by double-quotation marks

".*?"

• strings surrounded by [ ]

\[[^\[]*?\]

• variable names

[a-zA-Z_][a-zA-Z_0-9]*

• IP addresses

([0-9]{1,3})\.([0-9]{1,3})\.([0-9]{1,3})\.([0-9]{1,3})

• URL

(\S+)://([^:/]+)(:(\d+))?(/[^#\s]*)(#(\S+))?

• lines followed by a tab

\t.*$

• Hiragana

[\x{3041}-\x{309e}]

• Full-width Katakana

[\x{309b}-\x{309c}\x{30a1}-\x{30fe}]

• Half-width Kana

[\x{ff61}-\x{ff9f}]

• CJK ideographs

[\x{3400}-\x{9fff}\x{f900}-\x{fa2d}]

• CJK ideograph marks

[\x{3000}-\x{3037}]

• Hangul

[\x{1100}-\x{11f9}\x{3131}-\x{318e}\x{ac00}-\x{d7a3}]

• Insert // at start of lines

Find: ^

Replace with: //

• Remove // at start of lines

Find: ^//

Replace:

• Remove trailing whitespaces

Find: \s+?$

Replace with:

• Replace (abc) with [abc]

Find: \((.*?)\)

Replace: \[\1\]

• Replace <H3 ...> with <H4 ...>

Find: <H3(.*?)>

Replace: <H4\1>

• Replace 9/13/2003 with 2003.9.13

Find: ([0-9]{1,2})/([0-9]{1,2})/([0-9]{2,4})

Replace: \3\.\1\.\2

• Uppercase characters from a to z

Find: [a-z]

Replace: \U\0

• Capitalize all words

Find: ([a-zA-Z])([a-zA-Z]*)

Replace: \U\1\L\2