Golang ก็เหมือนภาษาอื่น ๆ คือจะมี IF, ELSE, FOR LOOPS, SWITH CASE อื่น ๆ
IF, ELSE IF, ELSE คำสั่งหากินของทุก ๆ ภาษา เกือบจะถูกเรียกว่า AI
อธิบายรวดเดียวกันไปเลย ด้วยโค๊ดข้างล่างนี้
// if condition_that_evaluates_to_boolean{
// perform action1
// }else if condition_that_evaluates_to_boolean{
// perform action2
// }else{
// perform action3
// }
price, inStock := 100, true
if price >= 80 { // parenthesis are no required to enclose the testing condition
fmt.Println("Too Expensive")
}
if price <= 100 && inStock == true { //the same with: if price <= 100 && inStock { }
fmt.Println("Buy it!")
}
// In Go there is not such a thing like the Truthiness of a variable.
// Error:
// if price {
// fmt.Println("We have price!")
// }
// only one if branch will be executed
if price < 100 {
fmt.Println("It's cheap!")
} else if price == 100 {
fmt.Println("On the edge")
} else { //executed only once if all the if branches are false (it's optional)
fmt.Println("It's Expensive!")
}Simple IF
อธิบายรวดเดียวกันไปเลย ด้วยโค๊ดข้างล่างนี้ ง่ายดี
package main
import (
"fmt"
"strconv"
)
func main() {
// converting string to int:
i, err := strconv.Atoi("45")
// error handling
if err != nil {
fmt.Println(err)
} else {
fmt.Println(i)
}
// simple (short) statement -> the same effect as the above code
// i and err are variables scoped to the if statement only
if i, err := strconv.Atoi("34"); err == nil {
fmt.Println("No error. i is ", i)
} else {
fmt.Println(err)
}
}For Loops การวนทำ ตามจำนวนข้อมูล
อธิบายรวดเดียวกันไปเลย ด้วยโค๊ดข้างล่างนี้ ง่ายดี
package main
import "fmt"
func main() {
// printing numbers from 0 to 9
for i := 0; i < 10; i++ {
fmt.Println(i)
}
// has the same effect as a while loop in other languages
// there is no while loop in Go
j := 10
for j >= 0 {
fmt.Println(j)
j--
}
// handling of multiple variables in a for loop
for i, j := 0, 100; i < 10; i, j = i+1, j+1 {
fmt.Printf("i = %v, j = %v\n", i, j)
}
// infinite loop
// sum := 0
// for {
// sum++
// }
// fmt.Println(sum) //this line is never reached
}หากต้องการที่จะ break (หยุดการทำงาน) หรือ continue (ต่อเนื่อง จะข้ามรอบการทำงานนั้น) จะทำอย่างไร
//** CONTINUE STATEMENT **//
// It works just the same as in C, Java or Python.
// The continue statement rejects all the remaining statements in the current iteration of the loop
// and moves the control back to the top of the loop.
// printing even numbers less than or equal to 10
for i := 1; i <= 10; i++ {
if i%2 != 0 {
continue // skipping the remaining code in this iteration
}
fmt.Println(i)
}
// **BREAK STATEMENT **//
// It is used to terminate the innermost for or switch statement.
// It works just the same as in C, Java or Python.
// finding 10 numbers divisible by 13
count := 0
for i := 0; true; i++ {
if i%13 == 0 {
fmt.Printf("%d is divisible by 13\n", i)
count++
}
if count == 10 { //if 10 numbers were found, break!
break //it breaks the current loop (inner loop if there are more loops)
}
}
// the break statement is not terminating the program entirely;
fmt.Println("Just a message after the for loop")จะลืมได้ไง Switch Statement
package main
import "fmt"
func main() {
language := "golang"
switch language {
case "Python": //values must be comparable (compare string to string)
fmt.Println("You are learning Python! You don't use { } but indentation !! ")
// an implicit break is added here
case "Go", "golang": //compare language with "Go" OR "golang"
fmt.Println("Good, Go for Go!. You are using {}!")
default:
// the default clause the equivalent of the else clause of an if statement
// and gets executed if no testing condition is true.
fmt.Println("Any other programming language is a good start!")
}
n := 5
// comparing the result of an expression which is bool to another bool value
switch true {
case n%2 == 0:
fmt.Println("Even!")
case n%2 != 0:
fmt.Println("Odd!")
default:
fmt.Println("Never here!")
}
//** Switch simple statement **//
// Syntax: statement (n:=10), semicolon and a switch condition
//(true in this case, we are comparing boolean expressions that return true)
// we can remove the word "true" because it's the default
switch n := 10; true {
case n > 0:
fmt.Println("Positive")
case n < 0:
fmt.Println("Negative")
default:
fmt.Println("Zero")
}
}