GO語言-基礎語法：條件判斷

1. IF判斷(aa.txt內容：asdfgh。bb.txt內容：12345)

package main

import (
    "io/ioutil"
    "fmt"
)

func main() {
    const filename1, filename2 = "aa.txt", "bb.txt"

    
    contents, err := ioutil.ReadFile(filename1) 
    if err != nil {
        fmt.Println(err)
    } else{
        fmt.Printf("%s\n", contents)
    }
    

    fmt.Printf("%s\n", contents) //打印出filename1的內容

    if contents, err := ioutil.ReadFile(filename2);err != nil {
        fmt.Println(err)
    } else {
        fmt.Printf("%s\n", contents)
    }

    fmt.Printf("%s\n", contents) //仍是打印出filename1的內容，filename2在if條件內，跳出IF以後失效（IP內部賦值，只對本次IF有效）
}

打印結果;

asdfgh
asdfgh
12345
asdfgh
[Finished in 0.6s]

 2. switch

package main

import (
    "fmt"
)

//定義函數：grade：函數名。score：傳入的變量，類型是int。string：函數返回的類型。
func grade(score int) string {
    g := ""
    switch {
    case score < 0 || score > 100:
         panic(fmt.Sprintf(
             "Wrong score: %d", score))
    case score < 60:
        g = "F"
    case score < 80:
        g = "C"
    case score < 90:
        g = "B"
    case score <= 100:
        g = "A"
    default://在本次switch中能夠不寫default，由於第一個case已經判斷了因此的異常
         panic(fmt.Sprintf(
             "Wrong score: %d", score))
    }

    return g
}

func main() {
    fmt.Println(grade(50),grade(60),grade(90),grade(10))
}

打印結果：

F C A F
[Finished in 0.7s]