重溫Golang-基礎知識
1 基礎知識
1.1 包
package main
import (
"fmt"
// 可以引入多個包
)
1.2 註釋
// 單行註釋
/*
多行註釋
*/
- 查看某個包裏的函數的作用(mac系統下)。
$ go doc fmt.Println
func Println(a ...interface{}) (n int, err error)
Println formats using the default formats for its operands and writes to
standard output. Spaces are always added between operands and a newline is
appended. It returns the number of bytes written and any write error
encountered.
- 編譯與運行
$ go run hello.go
1.3 變量
- 常用變量類型
// 常用變量類型
// int float bool string
// 常用 int 類型和範圍
// uint8 : unsigned 8-bit integers (0 to 255)
// uint16 : unsigned 16-bit integers (0 to 65535)
// uint32 : unsigned 32-bit integers (0 to 4294967295)
// uint64 : unsigned 64-bit integers (0 to 18446744073709551615)
// int8 : signed 8-bit integers (-128 to 127)
// int16 : signed 16-bit integers (-32768 to 32767)
// int32 : signed 32-bit integers (-2147483648 to 2147483647)
// int64 : signed 64-bit integers (-9223372036854775808 to
// 9223372036854775807)
// 常用 float 類型
//float32, float64
- 變量聲明和賦值
先聲明,再賦值。
var age int64
var pi float64
var married bool
var name string
age = 0
pi = 3.14
married = true
name = "weizheng"
邊聲明,邊賦值。
var age int64 = 0 // 顯性聲明
var pi float64 = 3.14 // 顯性聲明
var married bool = true // 顯性聲明
var name = "weizheng" // 隱性聲明
多變量聲明。
var a, b int = 1, 2
var(
age int64 = 0
pi float64 = 3.14
married bool = true
name = "weizheng"
)
另外的聲明方式。
num1 := 1
等同於
var num2 = 1
初始值。
var i int // 初始值 0
var f float64 // 初始值 0
var b bool // 初始值 false
var s string // 初始值 ""
1.4 運算符
// +, -, *, /, %
fmt.Println("6 + 4 =", 6+4)
fmt.Println("6 - 4 =", 6-4)
fmt.Println("6 * 4 =", 6*4)
fmt.Println("6 / 4 =", 6/4)
fmt.Println("6 % 4 =", 6%4)