8. golang 基本類型轉換

golang 類型轉換只能顯性轉換 不能自動轉換

 基本數據類型間的轉換

	var x1 int = 2
	var x2 int16
	var x3 int8

	x2 = 200 + x1
	x3 = 200 + x1

.\test.go:3:8: imported and not used: "fmt"

.\test.go:21:5: cannot use 200 + x1 (type int) as type int16 in assignment

.\test.go:22:5: cannot use 200 + x1 (type int) as type int8 in assignment

	var x1 int = 2

	var x2 int16

	var x3 int8

	x2 = 200 + int16(x1)

	x3 = 200 + int8(x1)

.\test.go:22:11: constant 200 overflows int8

基本數據類型和 string 之間的轉換

1. 使用 fmt.sprintf 函數進行

package main

import "fmt"

func main() {
	var x1 int = 88
	var x2 float32 = 3.45
	var x3 string

	x3 = fmt.Sprintf("this is a int  %d \n", x1)   //注意一定要使用雙引號
	fmt.Print(x3)
	x3 = fmt.Sprintf("this is a  float str %f \n", x2)
	fmt.Print(x3)
}

2. 使用 strconv 函數

package main

import (
	"fmt"
	"strconv"
)

func main() {
	var xx int = 123

	s := strconv.FormatInt(int64(xx), 16)
	fmt.Print(s)

}

 

字符串string 轉換為 基本數據類型

使用strconv 內容

package main

import (
	"fmt"
	"strconv"
)

func main() {
	var xx string = "1232123"
	xxx, _ := strconv.ParseInt(xx, 10, 32)
	fmt.Printf("this xxx is %T  %d", xxx, xxx)
// this xxx is int64  1232123


}

只能返回64位 如果需要32位 要自己在進行一次轉換


注意事項

字符串強行轉換為int  會有以下狀況

package main

import (

	"fmt"

	"strconv"

)

func main() {

	var xx string = "hello"

	xxx, _ := strconv.ParseInt(xx, 10, 32)

	fmt.Printf("this xxx is %T  %d", xxx, xxx)

// this xxx is int64  0

}