它应该给编译器错误，因为您试图在此处将string分配给char:

It should give compiler error because you are trying to assign a string to char here:

textBox1.Text[1] = "welcome to ***";

Text属性的类型为string，当您在string上使用索引器时，它会在该位置提供char.而且字符串是不可变的，因此您不能在不创建新字符串的情况下真正更改特定位置的字符.

Text property is of type string, when you use indexer on a string it gives you the char at that position. And also string is immutable so you can't really change a character at specific position without creating a new string.

您应该像这样直接设置Text:

You should set the Text directly like this:

textBox1.Text = "welcome to ***";

或者，如果字符串数组中有多行，则应设置Lines属性:

Or if you have more than one line in an array of string you should set the Lines property:

var lines = new [] { "foo", "bar" };
textBox1.Lines = lines;