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 did you define the keyword as var , or is defined as Let it?

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

For example, the PI can beπdefined as Letorvar.

letπ= 3.14159

varπ= 3.14159

The above code compiles without error. But from a business logic perspective,πshould be defined as a constant ( Let), because on the one hand constant ( Let) can not be modified, in addition to the use of constants in the program ( Let) can improve the readability of the program.

I think: In principle, first use Let , it has a lot of advantages, can prevent the program to run the process of unnecessary modification, 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?