Question

I faced a strange confusion today. Although I read the difference between String and string in C# in this post : What is the difference between String and string in C#?. But when I try to use String with capital letter without using the namespace System, it was not recognized. Like

This code works,

using System;

String s = "";

But without using System, it gives error.

Whereas string with small letter works with and without using the System namespace.

If String and string are same things then why one works only with its namespace and other works with and without namespace as well.

Answer 1

string is a C# construct that translates, during compilation to System.String.

Every C# program default has:

using string = System.String;
using char = System.Char;
using int = System.Int32;
using double = System.Double;

System.String is the class. You can’t use the type String without having access to the System namespace (so, either fully qualified as System.String, or with a using System; directive).