go for range坑和閉包坑
阿新 • • 發佈:2018-12-22
看程式:
package main
import (
"fmt"
"time"
)
func main() {
str := []string{"I","like","Golang"}
for _, v := range str{
v += "good"
}
for k, v := range str{
fmt.Println(k, v)
}
time.Sleep(1e9)
}
結果:
0 I
1 like
2 Golang
想一想,為什麼。
再看:
package main
import (
"fmt"
"time"
)
func main() {
str := []string{"I","like","Golang"}
for k, v := range str{
fmt.Println(&k, &v)
}
time.Sleep(1e9)
}
結果:
0xc000012050 0xc00000e1e0
0xc000012050 0xc00000e1e0
0xc000012050 0xc00000e1e0
想一想,為什麼。
再看:
package main import ( "fmt" "time" ) func main() { str := []string{"I","like","Golang"} for k, v := range str{ str = append(str, "good") fmt.Println(k, v) } time.Sleep(1e9) }
結果:
0 I
1 like
2 Golang
想一想, 為什麼。
再看:
package main
import (
"fmt"
"time"
)
func main() {
str := []string{"I","like","Golang"}
for k, v := range str{
go func(i int, s string){
fmt.Println(i, s, k, v)
}(k, v)
}
time.Sleep(1e9)
}
結果:
0 I 2 Golang
1 like 2 Golang
2 Golang 2 Golang
想一想,為什麼。
最後再看:
package main
import (
"fmt"
"time"
)
func main() {
str := []string{"I","like","Golang"}
for k, v := range str{
go func(i int, s string){
fmt.Println(i, s, k, v)
}(k, v)
time.Sleep(1e9)
}
time.Sleep(5e9)
}
結果:
0 I 0 I
1 like 1 like
2 Golang 2 Golang
想一想,為什麼。
不多說。