Regular Expressions Cookbook Book

Preface ix

1 Introduction to Regular Expressions 1

Regular Expressions Defined 1

Searching and Replacing with Regular Expressions 5

Tools for Working with Regular Expressions 7

2 Basic Regular Expression Skills 25

2.1 Match Literal Text 26

2.2 Match Nonprintable Characters 28

2.3 Match One of Many Characters 30

2.4 Match Any Character 34

2.5 Match Something at the Start and/or the End of a Line 36

2.6 Match Whole Words 41

2.7 Unicode Code Points, Properties, Blocks, and Scripts 43

2.8 Match One of Several Alternatives 55

2.9 Group and Capture Parts of the Match 57

2.10 Match Previously Matched Text Again 60

2.11 Capture and Name Parts of the Match 62

2.12 Repeat Part of the Regex a Certain Number of Times 64

2.13 Choose Minimal or Maximal Repetition 67

2.14 Eliminate Needless Backtracking 70

2.15 Prevent Runaway Repetition 72

2.16 Test for a Match Without Adding It to the Overall Match 75

2.17 Match One of Two Alternatives Based on a Condition 81

2.18 Add Comments to a Regular Expression 83

2.19 Insert Literal Text into the Replacement Text 85

2.20 Insert the Regex Match into the Replacement Text 87

2.21 Insert Part of the Regex Match into the Replacement Text 88

2.22 Insert Match Context into the Replacement Text 92

3 Programming with Regular Expressions 95

Programming Languages and Regex Flavors 95

3.1 Literal Regular Expressions in Source Code 100

3.2 Import the Regular Expression Library 106

3.3 Creating Regular Expression Objects 108

3.4 Setting Regular Expression Options 114

3.5 Test Whether a Match Can Be Found Within a Subject String 121

3.6 Test Whether a Regex Matches the Subject String Entirely 127

3.7Retrieve the Matched Text 132

3.8 Determine the Position and Length of the Match 138

3.9 Retrieve Part of the Matched Text 143

3.10 Retrieve a List of All Matches 150

3.11 Iterate over All Matches 155

3.12 Validate Matches in Procedural Code 161

3.13 Find a Match Within Another Match 165

3.14 Replace All Matches 169

3.15 Replace Matches Reusing Parts of the Match 176

3.16 Replace Matches with Replacements Generated in Code 181

3.17 Replace All Matches Within the Matches of Another Regex 187

3.18 Replace All Matches Between the Matches of Another Regex 189

3.19 Split a String 195

3.20 Split a String, Keeping the Regex Matches 203

3.21 Search Line by Line 208

4 Validation and Formatting 213

4.1 Validate Email Addresses 213

4.2 Validate and Format North American Phone Numbers 219

4.3 Validate International Phone Numbers 224

4.4 Validate Traditional Date Formats 226

4.5 Accurately Validate Traditional Date Formats 229

4.6 Validate Traditional Time Formats 234

4.7 Validate ISO 8601 Dates and Times 237

4.8 Limit Input to Alphanumeric Characters 241

4.9 Limit the Length of Text 244

4.10 Limit the Number of Lines in Text 248

4.11 Validate Affirmative Responses 253

4.12 Validate Social Security Numbers 254

4.13 Validate ISBNs 257

4.14 Validate ZIP Codes 264

4.15 Validate Canadian Postal Codes 265

4.16 Validate U.K. Postcodes 266

4.17 Find Addresses with Post Office Boxes 266

4.18 Reformat Names From "FirstName LastName" to "LastName, FirstName" 268

4.19 Validate Credit Card Numbers 271

4.20 European VAT Numbers 278

5 Words, Lines, and Special Characters 285

5.1 Find a Specific Word 285

5.2 Find Any of Multiple Words 288

5.3 Find Similar Words 290

5.4 Find All Except a Specific Word 294

5.5 Find Any Word Not Followed by a Specific Word 295

5.6 Find Any Word Not Preceded by a Specific Word 297

5.7 Find Words Near Each Other 300

5.8 Find Repeated Words 306

5.9 Remove Duplicate Lines 308

5.10 Match Complete Lines That Contain a Word 312

5.11 Match Complete Lines That Do Not Contain a Word 313

5.12 Trim Leading and Trailing Whitespace 314

5.13 Replace Repeated Whitespace with a Single Space 317

5.14 Escape Regular Expression Metacharacters 319

6 Numbers 323

6.1 Integer Numbers 323

6.2 Hexadecimal Numbers 326

6.3 Binary Numbers 329

6.4 Strip Leading Zeros 330

6.5 Numbers Within a Certain Range 331

6.6 Hexadecimal Numbers Within a Certain Range 337

6.7 Floating Point Numbers 340

6.8 Numbers with Thousand Separators 343

6.9 Roman Numerals 344

7 URLs, Paths, and Internet Addresses 347

7.1 Validating URLs 347

7.2 Finding URLs, Within Full Text 350

7.3 Finding Quoted URLs in Full Text 352

7.4 Finding URLs with Parentheses in Full Text 353

7.5 Turn URLs into Links 356

7.6 Validating URNs 356

7.7 Validating Generic URLs 358

7.8 Extracting the Scheme from a URL 364

7.9 Extracting the User from a URL 366

7.10 Extracting the Host from a URL 367

7.11 Extracting the Port from a URL 369

7.12 Extracting the Path from a URL 371

7.13 Extracting the Query from a URL 374

7.14 Extracting the Fragment from a URL 376

7.15 Validating Domain Names 376

7.16 Matching IPv4 Addresses 379

7.17 Matching IPv6 Addresses 381

7.18 Validate Windows Paths 395

7.19 Split Windows Paths into Their Parts 397

7.20 Extract the Drive Letter from a Windows Path 402

7.21 Extract the Server and Share from a UNC Path 403

7.22 Extract the Folder from a Windows Path 404

7.23 Extract the Filename from a Windows Path 406

7.24 Extract the File Extension from a Windows Path 407

7.25 Strip Invalid Characters from Filenames 408

8 Markup and Data Interchange 411

8.1 Find XML-Style Tags 417

8.2 Replace <b> Tags with <strong> 434

8.3 Remove All XML-Style Tags Except <em> and <strong> 438

8.4 Match XML Names 441

8.5 Convert Plain Text to HTML by Adding

and <br> Tags 447

8.6 Find a Specific Attribute in XML-Style Tags 450

8.7 Add a cellspacing Attribute to <table> Tags That Do Not Already Include It 455

8.8 Remove XML-Style Comments 458

8.9 Find Words Within XML-Style Comments 462

8.10 Change the Delimiter Used in CSV Files 466

8.11 Extract CSV Fields from a Specific Column 469

8.12 Match INI Section Headers 473

8.13 Match INI Section Blocks 475

8.14 Match INI Name-Value Pairs 476

Index 479