Data Types

Numeric Types

Go has integer and floating-point numbers for different kinds of arithmetic.

numeric type Numeric variables can use concrete types such as `int` and `float64`.

Numeric Types

count
numeric_types.go
Replay: real traced execution (multi-file project)
package main

import "fmt"

func main() {
	var count = 6
	var price float64 = 2.5
	total := float64(count) * price

	fmt.Println("count=", count)
	fmt.Println("total=", total)
}

package main

import "fmt"

func main() {
	var count = 3
	var price float64 = 2.5
	total := float64(count) * price

	fmt.Println("count=", count)
	fmt.Println("total=", total)
}

package main

import "fmt"

func main() {
	var count = 10
	var price float64 = 2.5
	total := float64(count) * price

	fmt.Println("count=", count)
	fmt.Println("total=", total)
}

  1. count ← 6, price ← 2.5, total ← 15

    5func main() {6  var count→ 6 = 6 //@count=3, 107  var price→ 2.5 float64 = 2.58  total→ 15 := float64(count6) * price2.5910  fmt.Println("count=", count6)11  fmt.Println("total=", total15)12}
    outputcount= 6
total= 15

  1. count ← 3, price ← 2.5, total ← 7.5

    5func main() {6  var count→ 3 = 37  var price→ 2.5 float64 = 2.58  total→ 7.5 := float64(count3) * price2.5910  fmt.Println("count=", count3)11  fmt.Println("total=", total7.5)12}
    outputcount= 3
total= 7.5

  1. count ← 10, price ← 2.5, total ← 25

    5func main() {6  var count→ 10 = 107  var price→ 2.5 float64 = 2.58  total→ 25 := float64(count10) * price2.5910  fmt.Println("count=", count10)11  fmt.Println("total=", total25)12}
    outputcount= 10
total= 25

Follow the Numbers

  1. count starts at 6.
  2. price is 2.5.
  3. float64(count) makes the integer usable with the floating-point price.
  4. total := float64(count) * price becomes 15.
  5. The program prints count= 6 and total= 15. | count | price | total | | --- | --- | --- | | 3 | 2.5 | 7.5 | | 6 | 2.5 | 15 | | 10 | 2.5 | 25 |

Exercise: numeric_types.go

Reproduce total= 15, then use the pinned counts 3 and 10 to predict each total.