Class String

Represents text as a sequence of UTF-16 code units.

Inheritance

Object

String

Implements

IComparable

IEnumerable

Inherited Members

Object.Equals(Object, Object)

Object.ReferenceEquals(Object, Object)

Object.GetHashCode()

Object.GetType()

Object.MemberwiseClone()

Namespace: System

Assembly: mscorlib.dll

Syntax

public sealed class String : IComparable, IEnumerable

Constructors

String(Char, Int32)

Initializes a new instance of the String class to the value indicated by a specified Unicode character repeated a specified number of times.

Declaration

public String(char c, int count)

Parameters

Type	Name	Description
Char	c	A Unicode character.
Int32	count	The number of times c occurs.

String(Char[])

Initializes a new instance of the String class to the value indicated by an array of Unicode characters.

Declaration

public String(char[] value)

Parameters

Type	Name	Description
Char[]	value	An array of Unicode characters.

String(Char[], Int32, Int32)

Initializes a new instance of the String class to the value indicated by an array of Unicode characters, a starting character position within that array, and a length.

Declaration

public String(char[] value, int startIndex, int length)

Parameters

Type	Name	Description
Char[]	value	An array of Unicode characters.
Int32	startIndex	The starting position within value.
Int32	length	The number of characters within value to use.

Fields

Empty

Represents the empty string. This field is read-only.

Declaration

public static readonly string Empty

Field Value

Type	Description
String

Properties

Chars[Int32]

Gets the Char object at a specified position in the current String object.

Declaration

public char this[int index] { get; }

Parameters

Type	Name	Description
Int32	index	A position in the current string.

Property Value

Type	Description
Char	The object at position index.

Length

Gets the number of characters in the current String object.

Declaration

public int Length { get; }

Property Value

Type	Description
Int32	The number of characters in the current string.

Methods

Compare(String, String)

Compares two specified String objects and returns an integer that indicates their relative position in the sort order.

Declaration

public static int Compare(string strA, string strB)

Parameters

Type	Name	Description
String	strA	The first string to compare.
String	strB	The second string to compare.

Returns

Type	Description
Int32	A 32-bit signed integer that indicates the lexical relationship between the two comparands.

CompareTo(Object)

Compares this instance with a specified Object and indicates whether this instance precedes, follows, or appears in the same position in the sort order as the specified Object.

Declaration

public int CompareTo(object value)

Parameters

Type	Name	Description
Object	value	An object that evaluates to a String.

Returns

Type	Description
Int32	A 32-bit signed integer that indicates whether this instance precedes, follows, or appears in the same position in the sort order as the value parameter.

CompareTo(String)

Compares this instance with a specified String object and indicates whether this instance precedes, follows, or appears in the same position in the sort order as the specified string.

Declaration

public int CompareTo(string strB)

Parameters

Type	Name	Description
String	strB	The string to compare with this instance.

Returns

Type	Description
Int32	A 32-bit signed integer that indicates whether this instance precedes, follows, or appears in the same position in the sort order as the strB parameter.

Concat(Object)

Creates the string representation of a specified object.

Declaration

public static string Concat(object arg0)

Parameters

Type	Name	Description
Object	arg0	The object to represent, or null.

Returns

Type	Description
String	The string representation of the value of arg0, or String.Empty if arg0 is null.

Concat(Object, Object)

Concatenates the string representations of two specified objects.

Declaration

public static string Concat(object arg0, object arg1)

Parameters

Type	Name	Description
Object	arg0	The first object to concatenate.
Object	arg1	The second object to concatenate.

Returns

Type	Description
String	The concatenated string representations of the values of arg0 and arg1.

Concat(Object, Object, Object)

Concatenates the string representations of three specified objects.

Declaration

public static string Concat(object arg0, object arg1, object arg2)

Parameters

Type	Name	Description
Object	arg0	The first object to concatenate.
Object	arg1	The second object to concatenate.
Object	arg2	The third object to concatenate.

Returns

Type	Description
String	The concatenated string representations of the values of arg0, arg1 and arg2.

Concat(Object[])

Concatenates the string representations of the elements in a specified Object array.

Declaration

public static string Concat(params object[] args)

Parameters

Type	Name	Description
Object[]	args	An object array that contains the elements to concatenate.

Returns

Type	Description
String	The concatenated string representations of the values of the elements in args.

Exceptions

Type	Condition
ArgumentNullException

Concat(String, String)

Concatenates two specified instances of String.

Declaration

public static string Concat(string str0, string str1)

Parameters

Type	Name	Description
String	str0	The first string to concatenate.
String	str1	The second string to concatenate.

Returns

Type	Description
String	The concatenation of str0 and str1.

Concat(String, String, String)

Concatenates three specified instances of String.

Declaration

public static string Concat(string str0, string str1, string str2)

Parameters

Type	Name	Description
String	str0	The first string to concatenate.
String	str1	The second string to concatenate.
String	str2	The third string to concatenate.

Returns

Type	Description
String	The concatenation of str0, str1 and str2.

Concat(String, String, String, String)

Concatenates four specified instances of String.

Declaration

public static string Concat(string str0, string str1, string str2, string str3)

Parameters

Type	Name	Description
String	str0	The first string to concatenate.
String	str1	The second string to concatenate.
String	str2	The third string to concatenate.
String	str3	The fourth string to concatenate.

Returns

Type	Description
String	The concatenation of str0, str1, str2 and str3.

Concat(String[])

Concatenates the elements of a specified String array.

Declaration

public static string Concat(params string[] values)

Parameters

Type	Name	Description
String[]	values	An array of string instances.

Returns

Type	Description
String	The concatenated elements of values.

Equals(Object)

Determines whether this instance and a specified object, which must also be a String object, have the same value.

Declaration

public override bool Equals(object obj)

Parameters

Type	Name	Description
Object	obj	The string to compare to this instance.

Returns

Type	Description
Boolean	true if obj is a String and its value is the same as this instance; otherwise, false. If obj is null, the method returns false.

Overrides

Object.Equals(Object)

Equals(String, String)

Determines whether two specified String objects have the same value.

Declaration

public static bool Equals(string a, string b)

Parameters

Type	Name	Description
String	a	The first string to compare, or null.
String	b	The second string to compare, or null.

Returns

Type	Description
Boolean	true if the value of a is the same as the value of b; otherwise, false. If both a and b are null, the method returns true.

Format(String, Object[])

Replaces the format items in a string with the string representations of corresponding objects in a specified array.

Declaration

public static string Format(string format, params object[] args)

Parameters

Type	Name	Description
String	format	A composite format string
Object[]	args	An object array that contains zero or more objects to format.

Returns

Type	Description
String	A copy of format in which the format items have been replaced by the string representation of the corresponding objects in args.

GetEnumerator()

Not supported in NanoFramework
Return an enumerator that iterate on each char of the string.

Declaration

public IEnumerator GetEnumerator()

Returns

Type	Description
IEnumerator	An IEnumerator object that can be used to iterate through the collection.

IndexOf(Char)

Reports the zero-based index of the first occurrence of the specified Unicode character in this string.

Declaration

public int IndexOf(char value)

Parameters

Type	Name	Description
Char	value	A Unicode character to seek.

Returns

Type	Description
Int32	The zero-based index position of value if that character is found, or -1 if it is not.

IndexOf(Char, Int32)

Reports the zero-based index of the first occurrence of the specified Unicode character in this string. The search starts at a specified character position.

Declaration

public int IndexOf(char value, int startIndex)

Parameters

Type	Name	Description
Char	value	A Unicode character to seek.
Int32	startIndex	The search starting position.

Returns

Type	Description
Int32	The zero-based index position of value from the start of the string if that character is found, or -1 if it is not.

IndexOf(Char, Int32, Int32)

Reports the zero-based index of the first occurrence of the specified character in this instance. The search starts at a specified character position and examines a specified number of character positions.

Declaration

public int IndexOf(char value, int startIndex, int count)

Parameters

Type	Name	Description
Char	value	A Unicode character to seek.
Int32	startIndex	The search starting position.
Int32	count	The number of character positions to examine.

Returns

Type	Description
Int32	The zero-based index position of value if that character is found, or -1 if it is not.

IndexOf(String)

Reports the zero-based index of the first occurrence of the specified string in this instance.

Declaration

public int IndexOf(string value)

Parameters

Type	Name	Description
String	value	The string to seek.

Returns

Type	Description
Int32	The zero-based index position of value if that string is found, or -1 if it is not. If value is String.Empty, the return value is 0.

IndexOf(String, Int32)

Reports the zero-based index of the first occurrence of the specified string in this instance. The search starts at a specified character position.

Declaration

public int IndexOf(string value, int startIndex)

Parameters

Type	Name	Description
String	value	The string to seek.
Int32	startIndex	The search starting position.

Returns

Type	Description
Int32	The zero-based index position of value from the start of the current instance if that string is found, or -1 if it is not. If value is String.Empty, the return value is startIndex.

IndexOf(String, Int32, Int32)

Reports the zero-based index of the first occurrence of the specified string in this instance. The search starts at a specified character position and examines a specified number of character positions.

Declaration

public int IndexOf(string value, int startIndex, int count)

Parameters

Type	Name	Description
String	value	The string to seek.
Int32	startIndex	The search starting position.
Int32	count	The number of character positions to examine.

Returns

Type	Description
Int32	The zero-based index position of value from the start of the current instance if that string is found, or -1 if it is not. If value is String.Empty, the return value is startIndex.

IndexOfAny(Char[])

Reports the zero-based index of the first occurrence in this instance of any character in a specified array of Unicode characters.

Declaration

public int IndexOfAny(char[] anyOf)

Parameters

Type	Name	Description
Char[]	anyOf	A Unicode character array containing one or more characters to seek.

Returns

Type	Description
Int32	The zero-based index position of the first occurrence in this instance where any character in anyOf was found; -1 if no character in anyOf was found.

IndexOfAny(Char[], Int32)

Reports the zero-based index of the first occurrence in this instance of any character in a specified array of Unicode characters. The search starts at a specified character position.

Declaration

public int IndexOfAny(char[] anyOf, int startIndex)

Parameters

Type	Name	Description
Char[]	anyOf	A Unicode character array containing one or more characters to seek.
Int32	startIndex	The search starting position.

Returns

Type	Description
Int32	The zero-based index position of the first occurrence in this instance where any character in anyOf was found; -1 if no character in anyOf was found.

IndexOfAny(Char[], Int32, Int32)

Reports the zero-based index of the first occurrence in this instance of any character in a specified array of Unicode characters. The search starts at a specified character position and examines a specified number of character positions.

Declaration

public int IndexOfAny(char[] anyOf, int startIndex, int count)

Parameters

Type	Name	Description
Char[]	anyOf	A Unicode character array containing one or more characters to seek.
Int32	startIndex	The search starting position.
Int32	count	The number of character positions to examine.

Returns

Type	Description
Int32	The zero-based index position of the first occurrence in this instance where any character in anyOf was found; -1 if no character in anyOf was found.

Intern(String)

Retrieves the system's reference to the specified String.

Declaration

public static string Intern(string str)

Parameters

Type	Name	Description
String	str	A string to search for in the intern pool.

Returns

Type	Description
String	The system's reference to str, if it is interned; otherwise, a new reference to a string with the value of str.

IsInterned(String)

Retrieves a reference to a specified String.

Declaration

public static string IsInterned(string str)

Parameters

Type	Name	Description
String	str	The string to search for in the intern pool.

Returns

Type	Description
String	A reference to str if it is in the common language runtime intern pool; otherwise, null.

IsNullOrEmpty(String)

Indicates whether the specified string is null or an empty string ("").

Declaration

public static bool IsNullOrEmpty(string value)

Parameters

Type	Name	Description
String	value	The string to test.

Returns

Type	Description
Boolean	true if the value parameter is null or an empty string (""); otherwise, false.

LastIndexOf(Char)

Reports the zero-based index position of the last occurrence of a specified Unicode character within this instance.

Declaration

public int LastIndexOf(char value)

Parameters

Type	Name	Description
Char	value	The Unicode character to seek.

Returns

Type	Description
Int32	The zero-based index position of value if that character is found, or -1 if it is not.

LastIndexOf(Char, Int32)

Reports the zero-based index position of the last occurrence of a specified Unicode character within this instance. The search starts at a specified character position and proceeds backward toward the beginning of the string.

Declaration

public int LastIndexOf(char value, int startIndex)

Parameters

Type	Name	Description
Char	value	The Unicode character to seek.
Int32	startIndex	The starting position of the search. The search proceeds from startIndex toward the beginning of this instance.

Returns

Type	Description
Int32	The zero-based index position of value if that character is found, or -1 if it is not found or if the current instance equals String.Empty.

LastIndexOf(Char, Int32, Int32)

Reports the zero-based index position of the last occurrence of the specified Unicode character in a substring within this instance. The search starts at a specified character position and proceeds backward toward the beginning of the string for a specified number of character positions.

Declaration

public int LastIndexOf(char value, int startIndex, int count)

Parameters

Type	Name	Description
Char	value	The Unicode character to seek.
Int32	startIndex	The starting position of the search. The search proceeds from startIndex toward the beginning of this instance.
Int32	count	The number of character positions to examine.

Returns

Type	Description
Int32	The zero-based index position of value if that character is found, or -1 if it is not found or if the current instance equals String.Empty.

LastIndexOf(String)

Reports the zero-based index position of the last occurrence of a specified string within this instance.

Declaration

public int LastIndexOf(string value)

Parameters

Type	Name	Description
String	value	The string to seek.

Returns

Type	Description
Int32	The zero-based starting index position of value if that string is found, or -1 if it is not. If value is String.Empty, the return value is the last index position in this instance.

LastIndexOf(String, Int32)

Reports the zero-based index position of the last occurrence of a specified string within this instance. The search starts at a specified character position and proceeds backward toward the beginning of the string.

Declaration

public int LastIndexOf(string value, int startIndex)

Parameters

Type	Name	Description
String	value	The string to seek.
Int32	startIndex	The search starting position. The search proceeds from startIndex toward the beginning of this instance.

Returns

Type	Description
Int32	The zero-based starting index position of value if that string is found, or -1 if it is not found or if the current instance equals String.Empty. If value is String.Empty, the return value is the smaller of startIndex and the last index position in this instance.

LastIndexOf(String, Int32, Int32)

Reports the zero-based index position of the last occurrence of a specified string within this instance. The search starts at a specified character position and proceeds backward toward the beginning of the string for a specified number of character positions.

Declaration

public int LastIndexOf(string value, int startIndex, int count)

Parameters

Type	Name	Description
String	value	The string to seek.
Int32	startIndex	The search starting position. The search proceeds from startIndex toward the beginning of this instance.
Int32	count	The number of character positions to examine.

Returns

Type	Description
Int32	The zero-based starting index position of value if that string is found, or -1 if it is not found or if the current instance equals String.Empty. If value is Empty, the return value is the smaller of startIndex and the last index position in this instance.

LastIndexOfAny(Char[])

Reports the zero-based index position of the last occurrence in this instance of one or more characters specified in a Unicode array.

Declaration

public int LastIndexOfAny(char[] anyOf)

Parameters

Type	Name	Description
Char[]	anyOf	A Unicode character array containing one or more characters to seek.

Returns

Type	Description
Int32	The index position of the last occurrence in this instance where any character in anyOf was found; -1 if no character in anyOf was found.

LastIndexOfAny(Char[], Int32)

Reports the zero-based index position of the last occurrence in this instance of one or more characters specified in a Unicode array. The search starts at a specified character position and proceeds backward toward the beginning of the string.

Declaration

public int LastIndexOfAny(char[] anyOf, int startIndex)

Parameters

Type	Name	Description
Char[]	anyOf	A Unicode character array containing one or more characters to seek.
Int32	startIndex	The search starting position. The search proceeds from startIndex toward the beginning of this instance.

Returns

Type	Description
Int32	The index position of the last occurrence in this instance where any character in anyOf was found; -1 if no character in anyOf was found or if the current instance equals String.Empty.

LastIndexOfAny(Char[], Int32, Int32)

Reports the zero-based index position of the last occurrence in this instance of one or more characters specified in a Unicode array. The search starts at a specified character position and proceeds backward toward the beginning of the string for a specified number of character positions.

Declaration

public int LastIndexOfAny(char[] anyOf, int startIndex, int count)

Parameters

Type	Name	Description
Char[]	anyOf	A Unicode character array containing one or more characters to seek.
Int32	startIndex	The search starting position. The search proceeds from startIndex toward the beginning of this instance.
Int32	count	The number of character positions to examine.

Returns

Type	Description
Int32	The index position of the last occurrence in this instance where any character in anyOf was found; -1 if no character in anyOf was found or if the current instance equals String.Empty.

PadLeft(Int32, Char)

Returns a new string that right-aligns the characters in this instance by padding them on the left with a specified Unicode character, for a specified total length.

Declaration

public string PadLeft(int totalWidth, char paddingChar = ' ')

Parameters

Type	Name	Description
Int32	totalWidth	The number of characters in the resulting string, equal to the number of original characters plus any additional padding characters.
Char	paddingChar	A Unicode padding character.

Returns

Type	Description
String

PadRight(Int32, Char)

Returns a new string that left-aligns the characters in this string by padding them on the right with a specified Unicode character, for a specified total length.

Declaration

public string PadRight(int totalWidth, char paddingChar = ' ')

Parameters

Type	Name	Description
Int32	totalWidth	The number of characters in the resulting string, equal to the number of original characters plus any additional padding characters.
Char	paddingChar	A Unicode padding character.

Returns

Type	Description
String

Split(Char[])

Splits a string into substrings that are based on the characters in an array.

Declaration

public string[] Split(params char[] separator)

Parameters

Type	Name	Description
Char[]	separator	A character array that delimits the substrings in this string, an empty array that contains no delimiters, or null.

Returns

Type	Description
String[]	An array whose elements contain the substrings from this instance that are delimited by one or more characters in separator. For more information, see the Remarks section.

Split(Char[], Int32)

Splits a string into a maximum number of substrings based on the characters in an array. You also specify the maximum number of substrings to return.

Declaration

public string[] Split(char[] separator, int count)

Parameters

Type	Name	Description
Char[]	separator	A character array that delimits the substrings in this string, an empty array that contains no delimiters, or null.
Int32	count	The maximum number of substrings to return.

Returns

Type	Description
String[]	An array whose elements contain the substrings in this instance that are delimited by one or more characters in separator. For more information, see the Remarks section.

Substring(Int32)

Retrieves a substring from this instance. The substring starts at a specified character position and continues to the end of the string.

Declaration

public string Substring(int startIndex)

Parameters

Type	Name	Description
Int32	startIndex	The zero-based starting character position of a substring in this instance.

Returns

Type	Description
String	A string that is equivalent to the substring that begins at startIndex in this instance, or Empty if startIndex is equal to the length of this instance.

Substring(Int32, Int32)

Retrieves a substring from this instance. The substring starts at a specified character position and has a specified length.

Declaration

public string Substring(int startIndex, int length)

Parameters

Type	Name	Description
Int32	startIndex	The zero-based starting character position of a substring in this instance.
Int32	length	The number of characters in the substring.

Returns

Type	Description
String	A string that is equivalent to the substring of length length that begins at startIndex in this instance, or Empty if startIndex is equal to the length of this instance and length is zero.

ToCharArray()

Copies the characters in this instance to a Unicode character array.

Declaration

public char[] ToCharArray()

Returns

Type	Description
Char[]	A Unicode character array whose elements are the individual characters of this instance. If this instance is an empty string, the returned array is empty and has a zero length.

ToCharArray(Int32, Int32)

Copies the characters in a specified substring in this instance to a Unicode character array.

Declaration

public char[] ToCharArray(int startIndex, int length)

Parameters

Type	Name	Description
Int32	startIndex	The starting position of a substring in this instance.
Int32	length	The length of the substring in this instance.

Returns

Type	Description
Char[]	A Unicode character array whose elements are the length number of characters in this instance starting from character position startIndex.

ToLower()

Returns a copy of this string converted to lowercase.

Declaration

public string ToLower()

Returns

Type	Description
String	A string in lowercase.

ToString()

Returns this instance of String; no actual conversion is performed.

Declaration

public override string ToString()

Returns

Type	Description
String	The current string.

Overrides

Object.ToString()

ToUpper()

Returns a copy of this string converted to uppercase.

Declaration

public string ToUpper()

Returns

Type	Description
String	The uppercase equivalent of the current string.

Trim()

Removes all leading and trailing white-space characters from the current String object.

Declaration

public string Trim()

Returns

Type	Description
String	The string that remains after all white-space characters are removed from the start and end of the current string. If no characters can be trimmed from the current instance, the method returns the current instance unchanged.

Trim(Char[])

Removes all leading and trailing occurrences of a set of characters specified in an array from the current String object.

Declaration

public string Trim(params char[] trimChars)

Parameters

Type	Name	Description
Char[]	trimChars	An array of Unicode characters to remove, or null.

Returns

Type	Description
String	The string that remains after all occurrences of the characters in the trimChars parameter are removed from the start and end of the current string. If trimChars is null or an empty array, white-space characters are removed instead. If no characters can be trimmed from the current instance, the method returns the current instance unchanged.

TrimEnd(Char[])

Removes all trailing occurrences of a set of characters specified in an array from the current String object.

Declaration

public string TrimEnd(params char[] trimChars)

Parameters

Type	Name	Description
Char[]	trimChars	An array of Unicode characters to remove, or null.

Returns

Type	Description
String	The string that remains after all occurrences of the characters in the trimChars parameter are removed from the end of the current string. If trimChars is null or an empty array, Unicode white-space characters are removed instead. If no characters can be trimmed from the current instance, the method returns the current instance unchanged.

TrimStart(Char[])

Removes all leading occurrences of a set of characters specified in an array from the current String object.

Declaration

public string TrimStart(params char[] trimChars)

Parameters

Type	Name	Description
Char[]	trimChars	An array of Unicode characters to remove, or null.

Returns

Type	Description
String	The string that remains after all occurrences of characters in the trimChars parameter are removed from the start of the current string. If trimChars is null or an empty array, white-space characters are removed instead.

Operators

Equality(String, String)

Determines whether two specified strings have the same value.

Declaration

public static bool operator ==(string a, string b)

Parameters

Type	Name	Description
String	a	The first string to compare, or null.
String	b	The second string to compare, or null.

Returns

Type	Description
Boolean	true if the value of a is the same as the value of b; otherwise, false.

Inequality(String, String)

Determines whether two specified strings have different values.

Declaration

public static bool operator !=(string a, string b)

Parameters

Type	Name	Description
String	a	The first string to compare, or null.
String	b	The second string to compare, or null.

Returns

Type	Description
Boolean	true if the value of a is different from the value of b; otherwise, false.

Implements

IComparable

IEnumerable

Extension Methods

LogDispatcher.GetCurrentClassLogger(Object)