Newb在这里努力成为一个业余爱好者。
我当前的项目使用方法，类，列表来显示书籍和评论，并允许用户在控制台视图中输入自己的评论。我已经建立了我的课程，他们现在正在工作，所以我暂时将他们删除，尽可能清楚地揭露我当前的问题。得到我的问题，我觉得我的程序很快变得很快，所以将一些代码移动到我称之为“选择”的方法似乎是个好主意。在我将代码移动到select方法之前，它按预期正常工作。但是现在我在测试时遇到错误：没有封闭的循环来破坏
特定错误发生在else if (command == "e"){break;}行
我已尝试将关键字'break'换成'continue'，但这不起作用。我已经浏览了网络和stackoverflow，但没有找到任何我能够理解的理解水平（我还是个新手）。
代码：
class Program
{
public void Play(){
Announcer(" \n\nProgram Name Goes Here \n\n");
while (true)
{
/*
* Allow user to display director of books (Three)
* allow user to select specific book with any comments it might have (2-4 comments)
* Allow user to enter a specific comment
* display book with new new added comment
* Allow user to exit book
* */
Select();
Console.Read();
}
}
public void Announcer(String strTxt){Console.Write(strTxt);}
public String GetString(String strData){
Console.WriteLine(strData);
return Console.ReadLine();//traffic control => back to program
}
public void Select(){
String command = GetString(" \n\n(V)eiw, (S)elect, (C)omment, (R)emove, (E)xit").ToLower();
if (command == "v")
{ Announcer(" \n\nEnter listing: ");
//ViewDirectory();//call view directory here
}
else if (command == "c")
{ Announcer(" \n\nEnter comment: "); }
else if (command == "s")
{
//we want to do a selectString method that returns length of selects here
String select = GetString(" \n\n(1)st Selection, (2)nd Selection, (3)rd book, (E)xit").ToLower();
if (select == "1")
{ Announcer(" \n\nDisplay book info + allow for user comment entering"); }
else if (select == "2")
{ Announcer(" \n\nDisplay book info + allow for user comment entering"); }
else if (select == "3")
{ Announcer(" \n\nDisplay book info + allow for user comment entering"); }
}
else if (command == "e") { break; }
else { Console.WriteLine("\n\nOopsy, I don't know that command! \n\n"); }
}
}
//public void ViewDirectory(){
// Console.WriteLine("stuff");
//}
答案 0 :(得分：4)
嗯，你不是一个循环，所以要终止方法的执行，关键字是'return'
答案 1 :(得分：2)
重构代码后，它不再知道它位于while循环内，因此break关键字是不必要的。
您使用break来终止程序，因此您需要执行其他操作才能退出while循环。您可以通过多种方式重构，但您可以尝试：
while (true)
{
var command
= GetString(" \n\n(V)eiw, (S)elect, (C)omment, (R)emove, (E)xit").ToLower();
if (command == "e")
break;
Select(command);
Console.Read();
}
将command传递给Select()，因此您的大多数逻辑仍在另一种方法中......只是不要在command == "e"中测试Select()。
答案 2 :(得分：1)
只需省略break;语句，因为不需要它，只有当您想要退出执行循环时才需要它。
答案 3 :(得分：1)
问题：您无法与if block分开，因为它未包含在任何loop中。
解决方案：您只需从if block返回条件的状态，以确保循环从调用方函数中断。
1。如果命令等于“e”则返回true，以便调用者断开循环。
2。 else返回false，以便循环继续。
class Program
{
public void Play(){
Announcer(" \n\nProgram Name Goes Here \n\n");
while (true)
{
/*
* Allow user to display director of books (Three)
* allow user to select specific book with any comments it might have (2-4 comments)
* Allow user to enter a specific comment
* display book with new new added comment
* Allow user to exit book
* */
if(Select())
break; //break if you get return value of Select() as true
Console.Read();
}
}
public bool Select(){
String command = GetString(" \n\n(V)eiw, (S)elect, (C)omment, (R)emove, (E)xit").ToLower();
if (command == "v")
{ Announcer(" \n\nEnter listing: ");
//ViewDirectory();//call view directory here
return false;
}
else if (command == "c")
{ Announcer(" \n\nEnter comment: "); return false;}
else if (command == "s")
{
//we want to do a selectString method that returns length of selects here
String select = GetString(" \n\n(1)st Selection, (2)nd Selection, (3)rd book, (E)xit").ToLower();
if (select == "1")
{ Announcer(" \n\nDisplay book info + allow for user comment entering"); }
else if (select == "2")
{ Announcer(" \n\nDisplay book info + allow for user comment entering"); }
else if (select == "3")
{ Announcer(" \n\nDisplay book info + allow for user comment entering"); }
return false;
}
else if (command == "e") { return true; }
else { Console.WriteLine("\n\nOopsy, I don't know that command! \n\n"); return
false; }
}
}
答案 4 :(得分：1)
中断关键字适用于循环或切换块。在Select方法中没有这样的语句。您可以从选择方法返回 true / false ，在播放方法中，您可以根据返回值调用 break ;
if(Select())
{
break;
}
答案 5 :(得分：1)
我会更新您的Select方法以返回一个布尔值，表明输入有效。然后，您可以按如下方式设置while条件：
while (Select())
{
/*
* Allow user to display director of books (Three)
* allow user to select specific book with any comments it might have (2-4 comments)
* Allow user to enter a specific comment
* display book with new new added comment
* Allow user to exit book
* */
Console.Read();
}
如果你有这样的话，我也会阻止使用其他许多东西，并将它们更新为使用switch / case。对于案例s，您也可以将其转换为单独的方法。
public bool Select()
{
bool isValid = true;
String command = GetString(" \n\n(V)eiw, (S)elect, (C)omment, (R)emove, (E)xit").ToLower();
switch (command)
{
case "v":
Announcer(" \n\nEnter listing: ");
//ViewDirectory();//call view directory here
break;
case "c":
Announcer(" \n\nEnter comment: ");
break;
case "s":
{
//we want to do a selectString method that returns length of selects here
String select = GetString(" \n\n(1)st Selection, (2)nd Selection, (3)rd book, (E)xit").ToLower()
switch (select)
{
case "1":
Announcer(" \n\nDisplay book info + allow for user comment entering");
break;
case "2":
Announcer(" \n\nDisplay book info + allow for user comment entering");
break;
case "3":
Announcer(" \n\nDisplay book info + allow for user comment entering");
break;
}
break;
}
case "e":
isValid = false;
break;
default:
Console.WriteLine("\n\nOopsy, I don't know that command! \n\n");
break;
}
return isValid;
}
答案 6 :(得分：1)
如果你有一个switch语句，不要在case语句之外放置任何东西，否则你会得到那个错误。
switch (val)
{
//this line should not be here
dosomething1(); //==>error
case "low":
dosomething2();
break;
case "high":
dosomething3();
break;
}