For each item, write a single regular expression that matches that item. Note that in ALL cases, the entire string must match without additional characters. 1. A string of digits that contains only digits and contains exactly two fives. Examples of acceptable strings include: "15445", "55", "05563" o The string should be rejected if it contains anything other than a digits. 2. A regular expression that matches a time expressed in the form "1:45 PM". o The hours part must be a number from 1 to 12, the minutes range from 00 to 59, and the time must indicate either AM or PM (uppercase only and preceded by exactly one space). 3. A regular expression that matches a string representing a comma separated list of variable names such as: hello, get_max, sum3 o A variable name consists of letters, digits, and underscores but cannot start with a digit. o There is exactly one space after every comma. No other spaces are allowed. o Commas and spaces are not allowed before the first name and after the last name.
For each item, write a single regular expression that matches that item. Note that in ALL cases, the entire string must match without additional characters. 1. A string of digits that contains only digits and contains exactly two fives. Examples of acceptable strings include: "15445", "55", "05563" o The string should be rejected if it contains anything other than a digits. 2. A regular expression that matches a time expressed in the form "1:45 PM". o The hours part must be a number from 1 to 12, the minutes range from 00 to 59, and the time must indicate either AM or PM (uppercase only and preceded by exactly one space). 3. A regular expression that matches a string representing a comma separated list of variable names such as: hello, get_max, sum3 o A variable name consists of letters, digits, and underscores but cannot start with a digit. o There is exactly one space after every comma. No other spaces are allowed. o Commas and spaces are not allowed before the first name and after the last name.
Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
Section: Chapter Questions
Problem 1PE
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
Transcribed Image Text:For each item, write a single regular expression that matches that item. Note that in ALL cases, the entire
string must match without additional characters.
1. A string of digits that contains only digits and contains exactly two fives. Examples of acceptable strings
include: "15445", "55", "05563"
o The string should be rejected if it contains anything other than a digits.
2. A regular expression that matches a time expressed in the form "1:45 PM".
o The hours part must be a number from 1 to 12, the minutes range from 00 to 59, and the time must
indicate either AM or PM (uppercase only and preceded by exactly one space).
3. A regular expression that matches a string representing a comma separated list of variable names such
as: hello, get_max, sum3
o A variable name consists of letters, digits, and underscores but cannot start with a digit.
o There is exactly one space after every comma. No other spaces are allowed.
o Commas and spaces are not allowed before the first name and after the last name.
o An empty string is considered a match.
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