Platform::String Class

Represents a sequential collection of Unicode characters that is used to represent text. For more information and examples, see Strings.

Syntax


public ref class String sealed : Object,  
    IDisposable,  
    IEquatable,  
    IPrintable  

Iterators

Two iterator functions, which are not members of the String class, can be used with the std::for_each template function to enumerate the characters in a String object.

Member Description
const char16* begin(String^ s) Returns a pointer to the beginning of the specified String object.
const char16* end(String^ s) Returns a pointer past the end of the specified String object.

Members

The String class inherits from Object, and the IDisposable, IEquatable, and IPrintable interfaces.

The String class also has the following types of members.

Constructors

Member Description
String::String Initializes a new instance of the String class.

Methods

The String class inherits the Equals(), Finalize(), GetHashCode(), GetType(), MemberwiseClose(), and ToString() methods from the Platform::Object Class. String also has the following methods.

Method Description
String::Begin Returns a pointer to the beginning of the current string.
String::CompareOrdinal Compares two String objects by evaluating the numeric values of the corresponding characters in the two string values represented by the objects.
String::Concat Concatenates the values of two String objects.
String::Data Returns a pointer to the beginning of the current string.
String::Dispose Frees or releases resources.
String::End Returns a pointer past the end of the current string.
String::Equals Indicates whether the specified object is equal to the current object.
String::GetHashCode Returns the hash code for this instance.
String::IsEmpty Indicates whether the current String object is empty.
String::IsFastPass Indicates whether the current String object is is participating in a fast pass operation. In a fast pass operation, reference counting is suspended.
String::Length Retrieves the length of the current String object.
String::ToString Returns a String object whose value is the same as the current string.

Operators

The String class has the following operators.

Member Description
String::operator== Operator Indicates whether two specifed String objects have the same value.
operator+ Operator Concatenates two String objects into a new String object.
String::operator> Operator Indicates whether the value of one String object is greater than the value of a second String object.
String::operator>= Operator Indicates whether the value of one String object is greater than or equal to the value of a second String object.
String::operator!= Operator Indicates whether two specifed String objects have different values.
String::operator< Operator Indicates whether the value of one String object is less than the value of a second String object.

Requirements

Minimum supported client: Windows 8

Minimum supported server: Windows Server 2012

Namespace: Platform

Header vccorlib.h (included by default)

String::Begin Method

Returns a pointer to the beginning of the current string.

Syntax


char16* Begin()  

Return Value

A pointer to the beginning of the current string.

String::CompareOrdinal Method

Compares two String objects by evaluating the numeric values of the corresponding characters in the two string values represented by the objects.

Syntax


int CompareOrdinal(  
           String^ str1,   
           String^ str2)  

Parameters

str1
The first String object.

str2
The second String object.

Return Value

An integer that indicates the lexical relationship between the two comparands. The following table lists the possible return values.

Value Condition
-1 str1 is less than str2.
0 str1 is equals str2.
1 str1 is greater than str2.

String::Concat Method

Concatenates the values of two String objects.

Syntax

String^ Concat( String^ str1, String^ str2)  

Parameters

str1
The first String object, or null.

str2
The second String object, or null.

Return Value

A new String^ object whose value is the concatenation of the values of str1 and str2.

If str1 is null and str2 is not, str1 is returned. If str2 is null and str1 is not, str2 is returned. If str1 and str2 are both null, the empty string (L"") is returned.

String::Data Method

Returns a pointer to the beginning of the object's data buffer as a C-style array of char16 (wchar_t) elements.

Syntax

const char16* Data()  

Return Value

A pointer to the beginning of a const``char16 array of Unicode characters (char16 is a typedef for wchar_t).

Remarks

Use this method to convert from Platform::String^ to wchar_t*. When the String object goes out of scope, the Data pointer is no longer guaranteed to be valid. To store the data beyond the lifetime of the original String object, use wcscpy_s to copy the array into memory that you have allocated yourself.

String::Dispose Method

Frees or releases resources.

Syntax


virtual override void Dispose()  

String::End Method

Returns a pointer past the end of the current string.

Syntax


char16* End()  

Return Value

A pointer to past the end of the current string.

Remarks

End() returns Begin() + Length.

String::Equals Method

Indicates whether the specified String has the same value as the current object.

Syntax


bool String::Equals(Object^ str);  

bool String::Equals(String^ str);  

Parameters

str
The object to compare.

Return Value

true if str is equal to the current object; otherwise, false.

Remarks

This method is equivalent to the String::CompareOrdinal. In the first overload, it is expected the str parameter can be cast to a String^ object.

String::GetHashCode Method

Returns the hash code for this instance.

Syntax


virtual override int GetHashCode()  

Return Value

The hash code for this instance.

String::IsEmpty Method

Indicates whether the current String object is empty.

Syntax

bool IsEmpty()  

Return Value

true if the current String object is null or the empty string (L""); otherwise, false.

String::IsFastPass Method

Indicates whether the current String object is is participating in a fast pass operation. In a fast pass operation, reference counting is suspended.

Syntax

bool IsFastPass();  

Return Value

true if the current String object is fast-past; otherwise, false.

Remarks

In a call to a function where a reference-counted object is a parameter, and the called function only reads that object, the compiler can safely suspend reference counting and improve calling performance. There is nothing useful that your code can do with this property. The system handles all the details.

String::Length Method

Retrieves the number of characters in the current String object.

Syntax

unsigned int Length()  

Return Value

The number of characters in the current String object.

Remarks

The length of a String with no characters is zero. The length of the following string is 5:

String^ str = "Hello";  
int len = str->Length(); //len = 5  

The character array returned by the String::Data has one additional character, which is the terminating NULL or ‘\0’. This character is also two bytes long.

String::operator+ Operator

Indicates whether two specifed String objects have the same value.

Syntax


bool String::operator+( String^ str1, String^ str2)  

Parameters

str1
The first String object.

str2
The second String object, whose contents will be appended to str1.

Return Value

true if str1 is equal to str2; otherwise, false.

Remarks

This operator creates a String^ object that contains the data from the two operands. Use it for convenience when extreme performance is not critical. A few calls to "+" in a function will probably not be noticeable, but if you are manipulating large objects or text data in a tight loop, then use the standard C++ mechanisms and types.

String::operator== Operator

Indicates whether two specified String objects have the same text value.

Syntax

bool String::operator==( String^ str1, String^ str2)  

Parameters

str1
The first String object to compare.

str2
The second String object to compare.

Return Value

true if the contents of str1 are equal to str2; otherwise, false.

Remarks

This operator is equivalent to String::CompareOrdinal.

String::operator>

Indicates whether the value of one String object is greater than the value of a second String object.

Syntax

bool String::operator>( String^ str1, String^ str2)  

Parameters

str1
The first String object.

str2
The second String object.

Return Value

true if the value of str1 is greater than the value of str2; otherwise, false.

Remarks

This operator is equivalent to explicitly calling String::CompareOrdinal and getting a result greater than zero.

String::operator>=

Indicates whether the value of one String object is greater than or equal to the value of a second String object.

Syntax

bool String::operator>=( String^ str1, String^ str2) 

Parameters

str1
The first String object.

str2
The second String object.

Return Value

true if the value of str1 is greater than or equal to the value of str2; otherwise, false.

String::operator!=

Indicates whether two specifed String objects have different values.

Syntax

bool String::operator!=( String^ str1, String^ str2)  

Parameters

str1
The first String object to compare.

str2
The second String object to compare.

Return Value

true if str1 is not equal to str2; otherwise, false.

String::operator<

Indicates whether the value of one String object is less than the value of a second String object.

Syntax

bool String::operator<( String^ str1, String^ str2)  

Parameters

str1
The first String object.

str2
The second String object.

Return Value

true if the value of str1 is less than the value of str2; otherwise, false.

String::String Constructor

Initializes a new instance of the String class with a copy of the input string data.

Syntax

String();    
String(char16* s)  
String(char16* s, unsigned int n)  

Parameters

s
A series of wide characters that initialize the string. char16

n
A number that specifies the length of the string.

Remarks

If performance is critical and you control the lifetime of the source string, you can use Platform::StringReference in place of String.

Example

String^ s = L”Hello!”;  

String::ToString

Returns a String object whose value is the same as the current string.

Syntax

String^ String::ToString()  

Return Value

A String object whose value is the same as the current string.

See Also

Platform namespace