Assignment 2

1. This question refers to the definition of integer literals in Java. What are valid integer literals?
   • 123
   • 123L
   • 0123
   • 00123
   • 0x123
   • 123x
   
   
2. Write a regular expression for each of the following languages over {a,b}:
• String of a's and b's that begin with a and end with b.
• Strings that have at least two a's.
• Strings that have an even number of a's.
• Strings that do not have two a's in a row.
• Strings that do not end with the substring ab.


3. Strings in C are delimited by double quotes ("), and may not contain newline characters. They may contain double quote or backslash characters if and only if those characters are "escaped" by a preceding backslash. Write a regular definition for strings in C.


4. Financial quantities in American notation have a leading dollar sign ($), an optional string of asterisks (*), a string of decimal digits, and an optional fractional part consisting of a decimal point (.) and two decimal digits. The string of digits to the left of the decimal point may consist of a single zero (0). Otherwise it must not start with a zero. If there are more than three digits to the left of the decimal point, groups of three (counting from the right) must be separated by commas (,). Example: $**1,234,567.89.
   
   
5. Convert the regular expressions of Questions 3 and 4 to DFAs.
   


6. Write a tokenizer for the toy language.