Swift 2.0 Learning Notes (Day 6)--what time do constants and variables use?

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Use Var or let?

In the course of our development, when is the definition of the keyword Var, or is it defined as let?

Actually AH all can satisfy our demand, then how should we choose?

For example, you can define PI π as let or var.

letπ= 3.14159

varπ= 3.14159

The above code compiles without error. However, from the business logic level, π should be defined as a constant (let), since constants (let) cannot be modified on the one hand, and the use of constants (let) in the program can improve the readability of the program.

I think: In principle, let is preferred, it has many advantages, it can prevent unnecessary changes in the process of running the program, improve the readability of the program. In particular, a let declaration is often used when referencing a data type declaration, although it is not a constant at the business level, but rather prevents the program from being incorrectly modified by its reference while it is running.

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Swift 2.0 Learning Notes (Day 6)--what time do constants and variables use?