Because the case difference is 32.

Because each letter has a corresponding ASCII. So letters can do operations.

That is, it can be encrypted with letters. You can move letters. etc

0. When shaping, it refers to the integer 0.

0' represents 0 in ASCII, and the corresponding value is 48.

"0" is a character indicating the end. This is usually used to indicate the end of the loop. His value in ASCII is 0.

But also on a simple calculator!