Golang 如何定义一个接口类型的切片，它可以用来存储混合类型的数据，又如何自定义错误信息输出，以及如何...
import (
"errors"
"fmt"
)
func main() {
<span style="font-size:14px"> //定义一个接口类型的切片，可以用来存储混合类型的数据</span>
in := make([]interface{}, 0)
in = append(in, 2, "Go", 8, "language", 'a', false, "A", 3.14)
var x1 int = in[0].(int)
var x2 string = in[1].(string)
var x3 int = in[2].(int)
var x4 string = in[3].(string)
var x5 int32 = in[4].(int32) //注意它是int32类型而不是uint8类型
var x6 bool = in[5].(bool)
var x7 string = in[6].(string)
var x8 float64 = in[7].(float64)
fmt.Println(" x1 = ", x1)
fmt.Println(" x2 = ", x2)
fmt.Println(" x3 = ", x3)
fmt.Println(" x4 = ", x4)
fmt.Println(" x5 = ", x5)
fmt.Println(" x6 = ", x6)
fmt.Println(" x7 = ", x7)
fmt.Println(" x8 = ", x8)
fmt.Println("in = ", in)
fmt.Println("===================================================================================")
data, err := concat(in...)
if err == nil {
fmt.Println("混合类型拼接字符串：", data)
} else {
fmt.Println("混合类型拼接字符串：", data)
}
}
<span style="font-size:14px">//变参函数concat有着不定数量和不确定类型的参数,把混合类型的多个值拼接成一个字符串</span>
func concat(args ...interface{}) (ret string, err error) {
for _, arg := range args {
switch v := arg.(type) {
case int:
ret = ret fmt.Sprintf("%v", v)
case int32:
ret = ret fmt.Sprintf("%v", v)
case int64:
ret = ret fmt.Sprintf("%v", v)
case bool:
ret = ret fmt.Sprintf("%v", v)
case string:
ret = ret fmt.Sprintf("%v", v)
case float32:
ret = ret fmt.Sprintf("%v", v)
case float64:
ret = ret fmt.Sprintf("%v", v)
default:
<span style="color:#FF0000">err = errors.New(fmt.Sprintf("%v", v) " data type has been not yet supported")</span> <span style="color:#FF0000"> // 自定义错误信息输出</span>return ret, err
}
}
return ret, nil
}
<span style="font-size:14px">调试控制台输出以下信息：</span>
2017/06/30 17:00:45 server.go:73: Using API v1
2017/06/30 17:00:45 debugger.go:97: launching process with args: [/root/code/go/src/contoso.org/book/debug]
API server listening at: 127.0.0.1:2345
2017/06/30 17:00:45 debugger.go:505: continuing
x1 = 2
x2 = Go
x3 = 8
x4 = language
x5 = 97
x6 = false
x7 = A
x8 = 3.14
in = [2 Go 8 language 97 false A 3.14]
===================================================================================
混合类型拼接字符串： 2Go8language97falseA3.14
<span style="font-size:14px">另外一个范例：</span>
package main
import (
"fmt"
)
func main() {
<span style="font-size:14px"> <span style="font-size:12px">//传入多个参数值直接调用变参函数，第1次传入7个参数值</span></span>
sum1 := sum(1, 2, 3, 4, 5, 6, 7)
<span style="font-size:14px"> <span style="font-size:12px">//传入多个参数值直接调用变参函数，第2次传入10个参数值</span></span>
sum2 := sum(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
fmt.Println("sum1 = ", sum1)
fmt.Println("sum2 = ", sum2)
//定义一个整数类型的切片params，并初始化它作为变参
params := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20}
<span style="color:#FF0000"><span style="font-size:12px">sum3 := sum(params...)</span></span>
fmt.Println("sum3 = ", sum3)
}
//变参函数sum有着不定数量的参数
<span style="color:#FF0000">func sum(args ...int) (ret int) {</span>
for _, arg := range args {
ret = arg
}
return //另外一种格式：return ret
}
<span style="font-size:14px">调试控制台输出以下信息：</span>
API server listening at: 127.0.0.1:2345
2017/06/30 17:38:52 debugger.go:505: continuing
sum1 = 28
sum2 = 55
sum3 = 210
<span style="font-size:14px">字符串的多种拼接方式范例：</span>
package main
import (
"bytes"
"fmt"
)
func main() {
<span style="font-size:14px">//方法一：字符串拼接</span>
/*
var str1 = "this is a testing string"
a := []byte(str1) <span style="font-size:12px"> // 字符串转[]uint8类型</span>
b := []byte(",and this is another appended testing string")
result := append(a, b...)
fmt.Println(string(result))
*/
<span style="font-size:14px">//方法二：字符串拼接</span>
var str1 = "this is a testing string"
var str2 = ",and this is another appended testing string"
var str3 = str1 str2
fmt.Println("str3 = ", str3)
<span style="font-size:14px">//方法三：字符串拼接(这种方式最快)</span>
var str4 = "hello,nice to meeting you"
var str5 = ",welcome to china again."
var buffer bytes.Buffer //Buffer是一个实现了读写方法的可变大小的字节缓冲
buffer.WriteString(str4)
buffer.WriteString(str5)
fmt.Println("字符串拼接结果: ", buffer.String())
<span style="font-size:14px"> //方法四：字符串混合值类型的拼接，直接使用NewBufferString创建缓存，直接使用另外一个NewBuffer创建缓存</span>
str6 := "Falling"
byte11 := []byte(" in ") //字符串转uint8类型的数组
byte12 := []byte{'L', 'o', 'v', 'e'} //uint8类的切片初始化
buf1 := bytes.NewBufferString(str6)
buf2 := bytes.NewBuffer(byte11)
buf3 := bytes.NewBuffer(byte12)
fmt.Println("字符串拼接结果：", buf1.String() buf2.String() buf3.String())
}
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