string和StringBuilder。

There are two types of strings in C#: string and StringBuilder.

String is an immutable type, and a new string object is created every time it is modified. Therefore, frequent modification of strings will generate a large number of garbage objects and affect performance. String is suitable for scenarios that are infrequently modified, such as string search, comparison, and splicing operations.

StringBuilder is a variable type that allows us to modify strings in place, avoiding the problem of frequently creating string objects and improving efficiency. StringBuilder is suitable for scenarios where strings are frequently modified, such as string splicing, insertion, deletion and other operations.

Here is a simple example demonstrating the use of StringBuilder:

StringBuilder sb = new StringBuilder();
for (int i = 0; i < 10000; i++)
{
    sb.Append(i.ToString());
}
string result = sb.ToString();

In the above example, we created a StringBuilder object and appended the string representation of 10,000 integers to it in a loop. Finally, we call the ToString() method to convert the StringBuilder object into a string. Since StringBuilder is a variable type, this operation is much more efficient than using string directly to splice strings.