该函数要求用户通过循环输入文件名的错误在哪里？
以下函数在 Visual C++ 中运行正确，但在 G++ 中运行不正确。
void OpenFile(ifstream *input)
{
string fileName = "";
while (true) {
cout << "Enter the filename: ";
cin >> fileName;
input->open(fileName.c_str());
cin.clear();
if (input->is_open()) break;
cout << "The filename does not exist. Try again." << endl;
}
}
在g++中，如果用户第一次正确输入文件名，程序就会执行。然而，如果用户错误地输入文件名，该函数将提示用户再次尝试输入，当用户在后续尝试中输入正确的文件名时，光标将移动到下一行，并且程序暂停。错误是什么？同样，它在 Visual C++ 中正确运行。
The following function runs correctly in Visual C++ but not in G++.
void OpenFile(ifstream *input)
{
string fileName = "";
while (true) {
cout << "Enter the filename: ";
cin >> fileName;
input->open(fileName.c_str());
cin.clear();
if (input->is_open()) break;
cout << "The filename does not exist. Try again." << endl;
}
}
In g++, if the user correctly enters the file name the first time, the program will execute. However, if the user incorrectly enters a file name, the function will prompt the user to enter another attempt, and when the user enters a correct file name on a subsequent attempt the cursor will move to the next line and the program pauses. What is the error? Again, this runs correctly in Visual C++.
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cin.clear()应该做什么？它应该重置任何错误输入中的状态，但希望输入不处于错误状态。
（否则，您试图打开一个没有名称的文件。）一个未定义的文件。）
关于程序的不同行为，我怀疑它是
与系统（或库）缓冲输入的方式相关。这
cin>> fileName通常不会返回，直到您输入换行符；但是，它不会从输入流中删除换行符。
根据输入的缓冲方式，这可能会导致它阻塞
（虽然我认为不应该）。尝试循环播放提示时
输入，最好使用
std::getline，然后提取从您已阅读的行中获取您需要的信息。 （在这种情况下，只需
去除两端的空白可能就足够了。）
What's the
cin.clear()supposed to be doing? It shoud reset any errorstate in the input, but hopefully, the input isn't in an error state.
(Otherwise, your trying to open a file without a name.)an undefined file.)
With regards to the varying behavior of the program, I suspect it is
linked to the way the system (or the library) is buffering input. The
cin >> fileNamewill typically not return until you enter a newline;it will not, however, remove the newline from the input stream.
Depending on how input is buffered, this could cause it to block
(although I don't think it should). When trying to loop on prompted
input, it is probably best to use
std::getline, then extract theinformation you need from the line you have read. (In this case, just
stripping white space at either end would probably be sufficient.)