System.String

Before examining the other string classes, this section quickly reviews some of the available methods on the String class.

System.String is a class specifically designed to store a string and allow a large number of operations on the string. Also, because of the importance of this data type, C# has its own keyword and associated syntax to make it particularly easy to manipulate strings using this class.

You can concatenate strings using operator overloads:

 string message1 = "Hello";  // returns "Hello" message1 += ", There"; // returns "Hello, There" string message2 = message1 + "!"; // returns "Hello, There!" 

C# also allows extraction of a particular character using an indexer-like syntax:

 char char4 = message[4]; // returns 'a'. Note the char is zero-indexed 

This enables you to perform such common tasks as replacing characters, removing whitespace, and capitalization. The following table introduces the key methods.

Method	Purpose
Compare	Compares the contents of strings, taking into account the culture (locale) in assessing equivalence between certain characters
CompareOrdinal	Same as Compare but doesn't take culture into account
Concat	Combines separate string instances into a single instance
CopyTo	Copies a specific number of characters from the selected index to a entirely new instance of an array
Format	Formats a string containing various values and specifiers for how each value should be formatted
IndexOf	Locates the first occurrence of a given substring or character in the string
IndexOfAny	Locates the first occurrence of any one of a set of characters in the string
Insert	Inserts a string instance into another string instance at a specified index
Join	Builds a new string by combining an array of strings
LastIndexOf	Same as IndexOf, but finds the last occurrence
LastIndexOfAny	Same as IndexOfAny, but finds the last occurrence
PadLeft	Pads out the string by adding a specified repeated character to the left side of the string
PadRight	Pads out the string by adding a specified repeated character to the right side of the string
Replace	Replaces occurrences of a given character or substring in the string with another character or substring
Split	Splits the string into an array of substrings, the breaks occurring wherever a given character occurs
Substring	Retrieves the substring starting at a specified position in the string
ToLower	Converts string to lowercase
ToUpper	Converts string to uppercase
Trim	Removes leading and trailing whitespace