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String::IndexOf Method (Char)

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

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

public:
int IndexOf(
	wchar_t value
)

Parameters

value
Type: System::Char

A Unicode character to seek.

Return Value

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

Index numbering starts from zero.

This method performs an ordinal (culture-insensitive) search, where a character is considered equivalent to another character only if their Unicode scalar values are the same. To perform a culture-sensitive search, use the CompareInfo::IndexOf method, where a Unicode scalar value representing a precomposed character, such as the ligature "Æ" (U+00C6), might be considered equivalent to any occurrence of the character's components in the correct sequence, such as "AE" (U+0041, U+0045), depending on the culture.

The following example demonstrates how you can search a String for a character using the IndexOf method.

using namespace System;

void main()
{
   // Create a Unicode String with 5 Greek Alpha characters.
   String^ szGreekAlpha = gcnew String(L'\x0391',5);

   // Create a Unicode String with a 3 Greek Omega characters.
   String^ szGreekOmega = L"\x03A9\x03A9\x03A9";

   String^ szGreekLetters = String::Concat(szGreekOmega, szGreekAlpha, 
                                           szGreekOmega->Clone());

   // Display the entire string.
   Console::WriteLine(szGreekLetters);

   // The first index of Alpha. 
   int ialpha = szGreekLetters->IndexOf( L'\x0391');
   // The first index of Omega. 
   int iomega = szGreekLetters->IndexOf(L'\x03A9');

   Console::WriteLine("First occurrence of the Greek letter Alpha: Index {0}", 
                      ialpha);
   Console::WriteLine("First occurrence of the Greek letter Omega: Index {0}", 
                      iomega);
}
// The example displays the following output: 
//       The string: OOO?????OOO 
//       First occurrence of the Greek letter Alpha: Index 3 
//       First occurrence of the Greek letter Omega: Index 0

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
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