String, or string, is a class that represents text. Technically its value is stored as a collection of char objects.

Since it is a class, it is a reference type. In some cases its behavior looks like a value type:

• A string reference will always point to the original object, so “modifying” one reference to a string will not affect other references
• Comparing strings with the equality operator (==) performs a value, not referential, comparison

Here are two examples of the first behavior (modifying one reference doesn’t affect the others):

// Example 1
string dog = "chihuahua";
string tinyDog = dog;
dog = "dalmation";
Console.WriteLine(dog);
// Output: "dalmation"
Console.WriteLine(tinyDog);
// Output: "chihuahua"

// Example 2
string s1 = "Hello ";
string s2 = s1;
s1 += "World";
System.Console.WriteLine(s1);
// Output: "Hello World"
System.Console.WriteLine(s2);
// Output: "Hello"

They can be explained by the fact that strings are immutable: they cannot be changed after they are created. Anything that appears to modify a string actually returns a new string object.

Here’s an example of the second behavior (value-like comparisons):

string s = "hello";
string t = "hello";
// b is true
bool b = (s == t);

Typically we want to compare strings by value, so this makes it easier to write in code and it also gives the C# compiler flexibility in how it implements the program (it doesn’t have to worry about where the actual string value is stored).