IndexOf Method (Char)

String.IndexOf Method (Char)

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

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(
	char 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.

The search for value is case-sensitive.

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

// Create a Unicode String with 5 Greek Alpha characters
String szGreekAlpha = new String('\u0319', 5);
// Create a Unicode String with a Greek Omega character
String szGreekOmega = new String(new char[] { '\u03A9', '\u03A9', '\u03A9' }, 2, 1);

String szGreekLetters = String.Concat(szGreekOmega, szGreekAlpha, szGreekOmega);

// Examine the result
outputBlock.Text += szGreekLetters + "\n";

// The first index of Alpha
int ialpha = szGreekLetters.IndexOf('\u0319');
// The last index of Omega
int iomega = szGreekLetters.LastIndexOf('\u03A9');

outputBlock.Text += "The Greek letter Alpha first appears at index " + ialpha +
    " and Omega last appears at index " + iomega + " in this String." + "\n";

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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