System.String.IndexOf Method

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.

Syntax

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

Parameters

value
A Unicode character to seek.
startIndex
The search starting position.
count
The number of character positions to examine.

Returns

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

Exceptions

TypeReason
ArgumentOutOfRangeException

startIndex or count is negative

-or-

startIndex + count is greater than the length of the current instance.

Remarks

The search begins at startIndex and continues to startIndex + count -1. The character at startIndex + count is not included in the search.

Index numbering starts from 0 (zero). The startIndex parameter can range from 0 to the length of the string instance.

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 System.Globalization.CompareInfo.IndexOf(string, char) 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.

Requirements

Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0, 4.0.0.0