C# StringExplore string methods: create, search and change strings with built-in code.
String.You look into a reflecting pool. A message suddenly appears. It is a string written upon the water's surface. Strings have words and characters.
String methods.Usually strings do not appear in reflecting pools. But we can manipulate any C# string with methods. New strings are returned.CompareCompareOrdinalCompareToConcatContainsCopyCopyToEndsWithEmptyEqualsFormatGetEnumeratorGetHashCodeIndexOfIndexOfAnyInsertInternIsInternedIsNormalizedIsNullOrEmptyIsNullOrWhiteSpaceJoinLastIndexOfLastIndexOfAnyLengthNormalizePadLeftPadRightRemoveReplaceSplitStartsWithSubstringToCharArrayToLowerToLowerInvariantToStringToUpperToUpperInvariantTrimTrimEndTrimStart
String interpolation.A string can be created with interpolated values in it. This is similar to string.Format but the syntax is different. We precede the string literal with a "$" sign.String Interpolation
Constructor.Strings are often reused, and passed around within a program. Methods like Replace() create new strings. But we can also create new ones with a constructor.String Constructor
Literals.These specify string data. We use quotes around literal data (characters). Literals are embedded in the program executable.Literal
Comparisons.Are two strings equal? In a Dictionary, we can use a StringComparer to change how keys are compared. We can ignore case.StringComparison, StringComparer
Char.A string contains data made up of individual characters. We deal with these chars in looping constructs. Accessing chars is a fast way to test strings.CharChar: Literal
Char methods.Many useful char methods are static. We call them on the "char" type, not on an instance of a char. Here are useful ones.char.IsControlchar.IsDigitchar.IsLetterOrDigitchar.IsLowerchar.IsPunctuationchar.IsSeparatorchar.IsWhiteSpacechar.ToLower
TextInfo.This type provides some helpful methods. We can convert a string To Title Case with ToTitleCase. No custom methods are needed.TextInfoTextInfo: ToTitleCase
Whitespace.Strings often contain newline or whitespace. We often need to check for these values. We use methods like IsNullOrWhitespace.NewLineLine CountWhitespace
Empty.An empty string has zero characters. Meanwhile a null string is no string at all. It is a reference that points to no memory location.Empty StringNull Strings
Parse, TryParse.When we see a string like "1230" we usually want its numeric form. We use TryParse for this. Here we transform strings into other types. Many routines are built-in.Parse
Conversions.We can convert a list into a string. And we can convert a string into a byte array. These are some of the most common conversions.Convert: List, StringConvert: String, Byte ArrayConvert: String, Int
Custom methods.Many string algorithms are composed from the built-in methods. With Substring calls we can Truncate strings. With ToCharArray we can change characters.Custom: IsUpper, IsLowerCustom: Reverse StringCustom: RightCustom: Sort String LengthsCustom: ToCharArray, Edit CharsCustom: TruncateCustom: Uppercase First Letters
Custom methods, chars.Here are some custom char-based string algorithms. We test individual chars in strings. We use arrays to look up char values.Custom: ASCII TableCustom: Char Lookup TableCustom: Char TestCustom: Combine CharsCustom: Count CharactersCustom: Count Letter FrequenciesCustom: Duplicate CharactersCustom: Get Char at IndexCustom: Remove Chars
Explanations.I explain concepts of strings. How do we append strings when there is no append method? We also learn to increment strings.String AppendString IncrementString Property
StringBuilder.This is not a string, but it is used to build up or change strings. For appending strings in a loop, we likely want to use StringBuilder.StringBuilder
StringBuilder, methods.Here are some methods that the StringBuilder class provides. Some optimizations based on StringBuilder are shown.StringBuilder: Append, AppendLineStringBuilder: AppendFormatStringBuilder: CapacityStringBuilder: ClearStringBuilder: ToString
Optimization.In typical usage strings are fast. But they are sometimes used in an inefficient way. Often reducing string allocations is helpful.Optimization
A review.A string is immutable. It can be used in many methods, and none of them have to worry about data changes. It never becomes invalid. This reduces copies.
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