Why ReadLine().ToUpper() and not ToUpper(ReadLine())?-CodePudding

Beginner question ahead.

If I want to convert input string (from console) to uppercase the syntax is the following one:

string text = Console.ReadLine().ToUpper();

Since "ToUpper()" is a method, I'm confused as to why console input is not its parameter?

string text = String.ToUpper(Console.ReadLine());

CodePudding user response：

Because ToUpper is declared like this according to the documentation:

public string ToUpper ();

Notice that it has no static modifier. This means that you should call it on an instance of a string, like the value returned by Console.ReadLine(), rather than on the class string. Also note that it takes no parameters (empty parentheses).

If it were declared like this instead:

public static string ToUpper (string s);

Then your way of calling it, string.ToUpper(Console.ReadLine()). In this case, it is static, so you should call it on the string class - the class in which it is declared, and it also takes a string parameter, which you have passed Console.ReadLine().

CodePudding user response：

There is no overload ToUpper() method that reads string as an argument and it is not even static method to use it like String.ToUpper().

There are only two overload methods that convert a string into upper.

ToUpper(): Returns a copy of this string converted to uppercase.
ToUpper(CultureInfo): Returns a copy of this string converted to uppercase, using the casing rules of the specified culture.