03-types.slide

Go Types



Brett McKay

* Declaring variables

How to declare a variable:

.play -edit 03-types/declaration.go /BEGIN OMIT/,/END OMIT/

What happens if you don't use a declared variable?

* Go Strings

- Are immutable
- Generally created using double quotes
- Raw strings are created with back ticks

.play -edit 03-types/string.go /BEGIN OMIT/,/END OMIT/

* Go Bools

*Values*
.play -edit 03-types/bool.go /BEGIN OMIT/,/END OMIT/

What will happen?
.play -edit 03-types/conflict.go /BEGIN OMIT/,/END OMIT/


* Type Systems

- Strong
- Weak

What is the difference between the two?

* Weak Typing

- Types are determined at run time
- Best match is used
- Cause problems when no match is possible

"1" + 1 = "11"
"!" - 1 = problem

* Strong Typing

- Types are determined at compile
- Types must match exactly
- Compiler errors occur when types don't match

"1" + 1 = error

Is Go strongly or weakly typed?

* Go Integers

*Signed*

- int8
- int16
- int32
- int64

*Unsigned*

- uint8
- uint16
- uint32
- uint64

* Continued

What will happen?
.play -edit 03-types/conflict-integer.go /BEGIN OMIT/,/END OMIT/

* Increment Example

What is the maximum number for int8?

What happens if you add 1?

* Continued

.play -edit 03-types/increment.go /BEGIN OMIT/,/END OMIT/

* Overflow assingment

What happens if you assign 128 to int8?

.play -edit 03-types/overflow.go /BEGIN OMIT/,/END OMIT/

* Implementation specific

- int either 32 bits or 64 bits
- uint same size as int

The size depends on the implementation of your system

* Go Floats

- float32
- float64

They exist and work how you would now expect

* Assignment

- What is the default value for each type?
- What happens if you divide a float by 0?