下面是一段c++代码:
int AskBase::ask_user(){
for (int tries_left = MAX_TRIES; tries_left;){
std::cout << prompt.c_str();
std::string response;
getline(std::cin, response);
if ("^Z" == response || std::cin.eof() || std::cin.bad())
return -9;
else if ("?V" == response)
std::cout << SSVID_ICON << SSVID << std::endl;
else if ("?" == response)
std::cout << "Enter ? for help, ?V for version, ^Z for exit.n"
else if (validate(response)){
answer_string = response;
return 1;
else
--tries_left;
}
return -9;
}
对于这些Scala应该是什么呢?
-
getline()
-
std::cin.eof()
-
std::cin.bad()
在Scala(和Java)中,到达eof
意味着在尝试读取时获得null
。我不知道cin.bad
是如何翻译的,但它可能是例外。
你的例子相当于:
def askUser( tries_left: Int = MAX_TRIES ):Int =
Console.readLine match {
case "^Z" | null => -9
case "?V" => {
println( SSVID_ICON + SSVID )
askUser( tries_left )
}
case "?" => {
println( "Enter ? for help, ?V for version, ^Z for exit.")
askUser( tries_left )
}
case response if validate(response) => {
answer_string = response
1
}
case _ => if( tries_left == 0) -9 else askUser( tries_left - 1)
}