Startbit-CoreUtilities 1.0.0

Startbit-CoreUtilities

A compact collection of C# extension methods simplifying common operations for DateTime, string, numeric, and color types, including conversions, calculations, validations, formatting, color transformations, palette generation, and more.

DateTime Extensions

Methods and Usage

• Quarter
  Returns the quarter of the year (1-4).
  int q = DateTime.Now.Quarter();

• IsLeapYear
  Checks if a given year is a leap year.
  bool leap = 2024.IsLeapYear();

• ToUnixTimestamp
  Converts DateTime to Unix timestamp (seconds since 1970-01-01 UTC).
  long unixTime = DateTime.Now.ToUnixTimestamp();

• ToDateTime
  Parses an ISO 8601 string to DateTime.
  DateTime? dt = "2025-08-25T15:30:00Z".ToDateTime();

• IsDateInRange
  Checks if a date is within a range inclusively.
  bool inRange = DateTime.Now.IsDateInRange(DateTime.Today, DateTime.Today.AddDays(7));

• StartOfWeek
  Gets the start date of the week (default Monday).
  DateTime startOfWeek = DateTime.Now.StartOfWeek();

• EndOfDay
  Returns the end of the day (23:59:59.9999999).
  DateTime end = DateTime.Now.EndOfDay();

• IsWeekend
  Checks if a date falls on weekend.
  bool weekend = DateTime.Now.IsWeekend();

• AddBusinessDays
  Adds business days, skipping weekends.
  DateTime nextBizDay = DateTime.Now.AddBusinessDays(5);

• IsToday
  Checks if a date is today.
  bool isToday = DateTime.Now.IsToday();

• Age
  Calculates age in years given a birthdate.
  int age = new DateTime(1990, 8, 25).Age();

• ToUtc
  Converts date to UTC.
  DateTime utc = DateTime.Now.ToUtc();

• ToCustomString
  Converts date to a formatted string.
  string formatted = DateTime.Now.ToCustomString("yyyy-MM-dd");

• DateOnly
  Returns the date with time truncated.
  DateTime dateOnly = DateTime.Now.DateOnly();

• IsWithinLastDays
  Checks if date is within the last N days.
  bool recent = DateTime.Now.AddDays(-3).IsWithinLastDays(5);

String Extensions

Methods and Usage

• Reverse
  Reverses the characters in the string.
  var reversed = "hello".Reverse(); // olleh

• WordCount
  Counts the number of words in the string.
  int count = "hello world".WordCount(); // 2

• ToTitleCase
  Converts string to title case (capitalize first letter of each word).
  string title = "hello world".ToTitleCase(); // Hello World

• RemoveDiacritics
  Removes accents and diacritics from characters.
  string normalized = "éèê".RemoveDiacritics(); // eee

• IsAlpha / IsAlphaNumeric / IsAlphaNumericWithUnderscore
  Checks if string contains only letters, letters/digits, or letters/digits/underscore.
  bool isAlpha = "abc".IsAlpha(); // true bool isAlnum = "abc123".IsAlphaNumeric(); // true bool isAlnumUnderscore = "abc_123".IsAlphaNumericWithUnderscore(); // true

• ToSlug
  Converts string to URL-friendly slug format.
  var slug = "Hello World!".ToSlug(); // hello-world

• SafeSubstring / LeftCharacter / RightCharacter
  Safely extracts substrings without exceptions.
  string left = "sample".LeftCharacter(3); // sam string right = "sample".RightCharacter(3); // ple

• CountOf
  Counts occurrences of a substring.
  int count = "banana".CountOf("an"); // 2

• RemoveNumbers / RemoveNonLetters
  Removes digits or non-letter characters.
  string noDigits = "abc123".RemoveNumbers(); // abc string lettersOnly = "abc123!".RemoveNonLetters(); // abc

• ToEnum<T>
  Converts string to enum value of type T.
  DayOfWeek day = "Friday".ToEnum<DayOfWeek>(); // Friday

• Repeat
  Repeats a string N times.
  var repeated = "ha".Repeat(3); // hahaha

• ContainsIgnoreCase
  Case-insensitive substring check.
  bool contains = "Hello".ContainsIgnoreCase("he"); // true

• SafeTrim
  Trims whitespace safely from a string.
  string trimmed = " ".SafeTrim(); // " "

• Truncate
  Truncates string to a maximum length.
  string truncated = "sample".Truncate(3); // sam

• CapitalizeFirstLetter
  Capitalizes the first letter only.
  string capitalized = "hello".CapitalizeFirstLetter(); // Hello

• ToBase64 / FromBase64
  Encode and decode base64 strings.
  string encoded = "data".ToBase64(); string decoded = encoded.FromBase64();

• RemoveWhiteSpace
  Removes all whitespace characters.
  string noSpaces = "a b c".RemoveWhiteSpace(); // abc

• HasDigits / HasLetters
  Checks if string contains digits or letters.
  bool hasDigits = "abc2".HasDigits(); // true bool hasLetters = "123".HasLetters(); // false

• ToIntSafe / ToDoubleSafe
  Safely parses to int or double with default fallback.
  int i = "123".ToIntSafe(); double d = "1.23".ToDoubleSafe();

• RemoveSpecialCharacters
  Removes all characters except letters and digits.
  string clean = "a!b@c#1".RemoveSpecialCharacters(); // abc1

• NormalizeLineEndings
  Normalizes line endings to platform default newlines.
  string normalized = "line1\r\nline2\rline3\n".NormalizeLineEndings();

• SplitLines
  Splits string into lines.
  string[] lines = "line1\r\nline2\nline3".SplitLines();

• InvertCase
  Returns the string with all letters in reverse case (a->A, A->a).
  string inverted = "Hello".InvertCase(); // hELLO

• EqualsIgnoreCase
  Returns true if the string equals another string ignoring case.
  bool equal = "hello".EqualsIgnoreCase("HELLO"); // true

• ExtractDigits
  Extracts only digit characters from a string.
  string digits = "abc123".ExtractDigits(); // 123

• ExtractLetters
  Extracts only letter characters from a string.
  string letters = "abc123".ExtractLetters(); // abc

• ExtractAlphaNumeric
  Extracts only letters and digits from a string.
  string alnum = "abc123_!".ExtractAlphaNumeric(); // abc123

• SubstringBetween
  Returns the substring between the first occurrences of two specified strings.
  string sub = "abc[start]middle[end]xyz".SubstringBetween("[start]", "[end]"); // middle

• IsNumeric
  Returns true if the string contains only numeric characters.
  bool isNum = "12345".IsNumeric(); // true

• IsValidEmail
  Returns true if the string is a valid email address format.
  bool isEmail = "user@example.com".IsValidEmail(); // true

• ReplaceFirst
  Replaces the first occurrence of a substring with another substring.
  string replacedFirst = "foo bar foo".ReplaceFirst("foo", "baz"); // baz bar foo

• ReplaceLast
  Replaces the last occurrence of a substring with another substring.
  string replacedLast = "foo bar foo".ReplaceLast("foo", "baz"); // foo bar baz

• JoinWith
  Joins a collection of strings into a single string separated by a specified separator.
  string joined = new[] { "one", "two", "three" }.JoinWith(", "); // one, two, three

Numeric Extensions

Methods and Usage

• IsInRange
  Checks if the integer value is within the inclusive range [min, max].
  bool check = 5.IsInRange(1, 10); // true

• IsPositive
  Returns true if the double value is greater than zero.
  bool check = 3.14.IsPositive(); // true

• IsNegative
  Returns true if the decimal value is less than zero.
  bool check = (-1.5m).IsNegative(); // true

• Clamp
  Clamps the integer value to be within the inclusive range of min and max.
  int clamped = 15.Clamp(0, 10); // 10

• ToOrdinalString
  Converts an integer to its ordinal string representation (e.g. 1 to "1st").
  string ordinal = 22.ToOrdinalString(); // "22nd"

• IsEven
  Returns true if the integer is even.
  bool check = 4.IsEven(); // true

• IsOdd
  Returns true if the integer is odd.
  bool check = 5.IsOdd(); // true

• RoundToDecimalPlaces
  Rounds the double value to the specified number of decimal places.
  double rounded = 3.14159.RoundToDecimalPlaces(2); // 3.14

• ToPercentageString
  Converts a double value to a percentage string with fixed decimals.
  string percent = 0.253.ToPercentageString(1); // "25.3%"

• ToThousandsSeparatedString
  Formats an integer with thousand separators for readability.
  string formatted = 1234567.ToThousandsSeparatedString(); // "1,234,567"

• IsWithinTolerance
  Checks if this double value is within the specified tolerance of another.
  bool check = 5.05.IsWithinTolerance(5, 0.1); // true

• Factorial
  Calculates the factorial of a non-negative integer.
  long fact = 5.Factorial(); // 120

• IsPrime
  Returns true if the integer is a prime number.
  bool check = 7.IsPrime(); // true

• ToRomanNumeral
  Converts an integer to its Roman numeral representation (1 to 3999).
  string roman = 1999.ToRomanNumeral(); // "MCMXCIX"

• ToByteArray
  Converts an integer to a byte array in little-endian order.
  byte[] bytes = 123.ToByteArray(); // { 123, 0, 0, 0 }

Color Extensions

Methods and Usage

• ToRgb
  Converts a HEX string (e.g. "#ff31ca") to an RGB struct.
  var rgb = "#ff31ca".ToRgb(); // RGB { R=255, G=49, B=202 }

• ToHex
  Converts an RGB struct to a HEX color string.
  var hex = rgb.ToHex(); // "#FF31CA"

• ToHsl
  Converts an RGB struct to an HSL struct.
  var hsl = rgb.ToHsl(); // HSL { H=309, S=1, L=0.6 }

• ToRgb (HSL)
  Converts an HSL struct back to an RGB struct.
  var rgb2 = hsl.ToRgb();

• ToHsv
  Converts an RGB struct to an HSV struct.
  var hsv = rgb.ToHsv();

• ToRgb (HSV)
  Converts an HSV struct back to RGB.
  var rgb3 = hsv.ToRgb();

• Complementary
  Returns the complementary color for an HSL struct (180° hue shift).
  var comp = hsl.Complementary();

• Monochromatic
  Generates a set of monochromatic HSL colors varying in lightness.
  var shades = hsl.Monochromatic(5);

• AdjustBrightness
  Adjusts brightness of an RGB color by a factor.
  var brighter = rgb.AdjustBrightness(1.2);

• AdjustSaturation
  Adjusts saturation of an HSL color by a factor.
  var lessSaturated = hsl.AdjustSaturation(0.7);

• InterpolateTo
  Linearly interpolates between two RGB colors by an amount (0 to 1).
  var midColor = rgb.InterpolateTo(otherRgb, 0.5);

• BlendWith
  Blends base RGB color with another by alpha transparency.
  var blended = rgb.BlendWith(otherRgb, 0.3);

• ToGrayscale
  Converts an RGB color to grayscale using luminosity calculations.
  var gray = rgb.ToGrayscale();

• Invert
  Inverts the colors of an RGB struct.
  var inverted = rgb.Invert();

• GetLuminance
  Calculates the luminance of an RGB color for contrast analysis.
  double luminance = rgb.GetLuminance();

• ContrastRatio
  Calculates contrast ratio between two RGB colors (1 to 21).
  double ratio = rgb.ContrastRatio(otherRgb);

• MeetsAaContrast
  Checks if two colors meet WCAG 2.1 AA contrast (min 4.5).
  bool passes = rgb.MeetsAaContrast(otherRgb);

Enumerable Extensions

Methods and Usage

• ChunkBy
  Splits a collection into chunks of a specified size, useful for batch processing or pagination.
  var chunks = myList.ChunkBy(10);

• EmptyIfNull
  Returns an empty enumerable if the source is null, to safely avoid null exceptions.
  var safeEnumerable = possiblyNullEnumerable.EmptyIfNull();

• DistinctBy
  Returns distinct elements from a collection based on a specified key selector.
  var distinctItems = myList.DistinctBy(x => x.Id);

• ElementAtOrDefaultSafe
  Safely gets the element at the given index or a default value if out of range.
  var item = myList.ElementAtOrDefaultSafe(5);

• ForEach
  Performs the specified action on each element in the collection.
  myList.ForEach(item => Console.WriteLine(item));

• SelectWithIndex
  Projects each element into a new form by incorporating the element's index.
  var indexedItems = myList.SelectWithIndex((item, index) => $"{index}: {item}");

• RandomElement
  Picks a random element from the list. Throws if the list is empty.
  var randomItem = myList.RandomElement();

• Flatten
  Flattens a sequence of sequences into a single sequence.
  var flatList = nestedList.Flatten();

Installation

Install via NuGet:

Install-Package Startbit-CoreUtilities

Usage

Add the namespace to your code:

using Startbit-CoreUtilities;

Then call any of the extension methods on the appropriate types (DateTime, int for year extensions, string).