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.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- value
- Type: System.Char
A Unicode character to seek.
Return Value
Type: System.Int32The 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";