go 语言入门

参见文章1，文章2

1.编译

go build test.go

2.运行

go run test.go

3.看帮助

go doc builtin
go doc fmt/fnv

4.运行测试

编写源代码even.go

/*
	this package is test for write package

*/
package even

// check value is even value
// if is even, return true, otherwise false	
func Even(value int) bool {
	return 0 == (value % 2)
}

func Odd(value int) bool {
	return 1 == (value % 2)
}

编写测试代码even_test.go

package even

import (
	"testing"
)

func TestEvent(t *testing.T) {
	if !Even(2) {
		t.Log("2 should be odd")
		t.Fail()
	}
}

func TestOdd(t *testing.T) {
	if !Odd(3) {
		t.Log("3 should be odd")
		t.Fail()
	}
}

运行测试

go test

5.创建包

创建源代码文件，在$GOROOT下的src\pkg\utils\ustackm目录下创建文件ustack.go

/**
   simulate stack, capacity is 10
**/
package ustack

import (
	"errors"
	strConvUtils "strconv"
)

const stackMax = 10

type UStack struct {
	index int
	datas [stackMax]int
}

func (s *UStack) Push(value int) (result int, err error) {
	if s.index > (stackMax - 1) {
		result = -1
		err = errors.New("exceed max size")
		return
	}
	s.datas[s.index] = value
	result = s.index
	s.index++
	return
}

func (s *UStack) Pop() (result int, err error) {
	if s.index < 1 {
		result = -2
		err = errors.New("exceed min size")
		return
	}
	result = s.datas[s.index-1]
	s.index--
	return
}

func (s *UStack) String() (str string) {
	for i := 0; i < s.index; i++ {
		str = str + "[" + strConvUtils.Itoa(i) + ":" + strConvUtils.Itoa(s.datas[i]) + "]"
	}
	return
}

注意包内的函数和类型能被外界访问，必须名字第一个字符大写

go build ustack.go

go install

将ustack.a放到$GOROOT下的pkg\windows_386\utils\ustack目录下或pkg\linux_386\utils\ustack

创建包方法另外一种方法

参见文章3，文章4

在环境变量中加入GOPATH，指定对应包目录（可以有多个目录），在下面建立src目录，作为包的目录

编写对应的go文件，比如上例的src\ustack\UStack.go

在任何目录执行

go install ustack

自动在对应的gopath目录下生成pkg目录

6.接口的写法

type IFactory interface {
	getRunApp() IRunApp
}

type AppTools struct {
	m_Factory FactoryImpl
}

type IRunApp interface {
	run()
}

type RunAppImpl struct {

}

type FactoryImpl struct {
	m_RunApp RunAppImpl
}


func (factory *FactoryImpl) getRunApp() IRunApp {
	return &factory.m_RunApp
}

func (runApp *RunAppImpl) run() {
}

func (appTools *AppTools) getFactory() IFactory {
	return &appTools.m_Factory
}

7编译链接

8g 123.go
8l -o 123.out 123.8

8得到操作系统目录分隔符

filepath.Separator

9判断文件或目录是否存在

func (appTools *AppTools) pathExists(pathName string) bool {
	if appTools.judgeEmptyStr(&pathName) {
		return false
	}
	_, err := ioutil.ReadDir(pathName)
	if nil != err {
		return false
	}
	return true
}

func (appTools *AppTools) fileExists(fileName string) bool {
	f, err := os.Open(fileName)
	if err != nil && os.IsNotExist(err) {
		return false
	}
	defer f.Close()
	return true
}

10.得到日期

func (appTools *AppTools) getCurrentTime() string {
	return time.Now().Format("2006-01-02 15:04:05")
}

11.字符串转为小写

strings.ToLower

12.拷贝文件函数

func (appTools *AppTools) copyFile(src, dst string) bool {
	srcFile, err := os.Open(src)
	if err != nil {
		appTools.log(fmt.Sprintln("Open", src, "failed", err.Error()))
		return false
	}
	defer srcFile.Close()

	dstFile, err := os.Create(dst)

	if err != nil {
		appTools.log(fmt.Sprintln("create", dst, "failed", err.Error()))
		return false
	}

	defer dstFile.Close()
	w, err := io.Copy(dstFile, srcFile)
	w = w + 1
	if nil != err {
		appTools.log(fmt.Sprintln("Copy", src, "to", dst, "failed", err.Error()))
		return false
	}

	return true
}

13.截取字符串

func (appTools *AppTools) substr(str string, start, count int) string {
	rs := []rune(str)
	rl := len(rs)
	end := 0

	if start < 0 {
		start = 0
	}

	if start > rl {
		return ""
	}
	if start < 0 {
		start = 0
	}
	if start > rl {
		start = rl
	}
	end = start + count
	if end > rl-1 {
		end = rl
	}
	return string(rs[start:end])
}

14.读写文件

    srcFile, err := os.OpenFile(hName, os.O_RDONLY, 0666)
	if nil != err {
		appTools.log(fmt.Sprintln("file", hName, "open failed", err.Error()))
		return
	}
	defer srcFile.Close()
	tempFile, err := os.OpenFile(tempFileName, os.O_APPEND|os.O_RDWR, 0666)
	if nil != err {
		appTools.log(fmt.Sprintln("file", tempFileName, "open failed", err.Error()))
		return
	}
	defer tempFile.Close()
	srcReader := bufio.NewReader(srcFile)
	destWriter := bufio.NewWriter(tempFile)
	defer destWriter.Flush()
	for {
			str, err := srcReader.ReadString('\n')
			if nil != err {
				if io.EOF != err {
					appTools.log(err.Error())
				}
				break
			}
			_, err = destWriter.WriteString(str)
			if nil != err {
				appTools.log(err.Error())
			}
		}
	}

15.字符串包含子字符串

// 包含
strings.Contains(str, substr)
// 在结尾
strings.HasSuffix(str, substr)
// 在头
strings.HasPrefix(str, substr)

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