Searches for the specified character and returns the zero-based index of the first occurrence within the entire source string.
The zero-based index of the first occurrence of value, if found, within source; otherwise, -1. Returns 0 (zero) if value is an ignorable character.
This method searches the source string from the beginning of the string to the end of the string.
This overload performs a culture-sensitive search. If value represents a precomposed Unicode character, such as the ligature "Æ" (U+00C6), it might be considered equivalent to any occurrence of its components in the correct sequence, such as "AE" (U+0041, U+0045), depending on the culture. To perform an ordinal (culture-insensitive) search, where a character is considered equivalent to another character only if their Unicode code points are the same, you should call an overload that has a parameter of type System.Globalization.CompareOptions and use the CompareOptions.Ordinal value. Unlike CompareInfo.IndexOf(string, char), which performs a culture-sensitive comparison, overloads of the string.IndexOf(char) method that search for a character perform an ordinal comparison and overloads that search for a string perform a culture-sensitive comparison.
When possible, you should use string comparison methods that have a parameter of type System.Globalization.CompareOptions to specify the kind of comparison expected. As a general rule, use linguistic options (using the current culture) for comparing strings displayed in the user interface and specify CompareOptions.Ordinal or CompareOptions.OrdinalIgnoreCase for security comparisons.