Core Java Programming Course- Character Classes in RegEx (regular expressions)

The video tutorial covers character classes in regular expressions, focusing on digit, word, and special characters. It explains the use of escape sequences in Java and demonstrates pattern matching with quantifiers. Practical examples include creating regex patterns for phone numbers and passwords, highlighting the use of non-digit and special character classes.

Which character class in regex is used to represent any single digit?

• \D

• \s

• \d

• \w

In Java, why might you encounter an error when using \d in a regex pattern?

• Because \d is a quantifier

• Because \d represents a word character

• Because \d is used for whitespace

• Because \d is not a valid escape sequence in Java

What does the quantifier {3} signify in a regex pattern?

• Match at most 3 occurrences of the preceding character

• Match any number of occurrences of the preceding character

• Match at least 3 occurrences of the preceding character

• Match exactly 3 occurrences of the preceding character

Which of the following is NOT a valid use of quantifiers in regex?

• Matching a specific number of characters

• Matching a range of characters

• Matching any number of characters

• Matching only special characters

How would you represent a phone number pattern that starts with 678 followed by any 7 digits?

• \d{10}

• 678\d{7}

• 678\w{7}

• \d{3}678\d{4}

Which regex pattern would match a password starting with 2 to 6 word characters followed by exactly 2 special characters?

• \w{2,6}\d{2}

• \s{2,6}\W{2}

• \d{2,6}\W{2}

• \w{2,6}\W{2}

What does the \W character class represent in regex?

• Any non-word character

• Any word character

• Any digit

• Any whitespace character