import "fmt"
func main() {
s := "asdlllajsd123{}#^$^#"
r := ""
for i := 0; i < len(s); i++ {
if IsAlnum(s[i]) {
r = r + string(s[i])
}
}
fmt.Println(r)
}
// IsAlnum 判断
func IsAlnum(b byte) bool {
return (b >= 'a' && b <= 'z') || (b >= 'A' && b <= 'Z') || (b >= '0' && b <= '9')
}