如何在 C++ 中将变量结果插入到字符串中
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How do I insert a variable result into a string in C++
提问by Natatos
I just started learning C++ in Qt and I was wondering how can I put a variables result in a string? I'm trying to use this for a simple application where someone puts their name in a text field then presses a button and it displays there name in a sentence. I know in objective-c it would be like,
我刚开始在 Qt 中学习 C++，我想知道如何将变量结果放入字符串中？我试图将它用于一个简单的应用程序，其中有人将他们的名字放在一个文本字段中，然后按下一个按钮，它会在一个句子中显示该名字。我知道在objective-c中它会像，
NSString *name = [NSString stringWithFormatting:@"Hello, %@", [nameField stringValue]];
[nameField setStringValue:name];
How would I go about doing something like this with C++? Thanks for the help
我将如何用 C++ 做这样的事情？谢谢您的帮助
采纳答案by K-ballo
You don′t mention what type your string is. If you are using the standard library then it would be something along the lines of
你没有提到你的字符串是什么类型。如果您使用的是标准库，那么它将类似于
std::string name = "Hello, " + nameField;
That works for concatenating strings, if you want to insert other complex types you can use a stringstream like this:
这适用于连接字符串，如果你想插入其他复杂类型，你可以使用这样的字符串流：
std::ostringstream stream;
stream << "Hello, " << nameField;
stream << ", here is an int " << 7;
std::string text = stream.str();
Qt probably has its own string types, which should work in a similar fashion.
Qt 可能有自己的字符串类型，应该以类似的方式工作。
回答by Ken Bloom
I assume we're talking about Qt's QStringclass here. In this case, you can use the argmethod:
我假设我们在QString这里谈论的是 Qt 的课程。在这种情况下，您可以使用以下arg方法：
int i; // current file's number
long total; // number of files to process
QString fileName; // current file's name
QString status = QString("Processing file %1 of %2: %3")
.arg(i).arg(total).arg(fileName);
See the QString documentationfor more details about the many overloads of the argmethod.
有关该方法的许多重载的更多详细信息，请参阅QString 文档arg。
回答by Andrew White
I would use a stringstreambut I'm not 100% sure how that fits into your NSString case...
我会使用stringstream但我不是 100% 确定它如何适合您的 NSString 案例......
stringstream ss (stringstream::in);
ss << "hello my name is " << nameField;
I think QStringhas some nifty helpers that might do the same thing...
我认为QString有一些漂亮的助手可以做同样的事情......
QString hello("hello ");
QString message = hello % nameField;
回答by Ken Bloom
You could use QString::sprintf. I haven't found a good example of it's use yet, though. (If someone else finds one, feel free to edit it in to this answer).
你可以使用QString::sprintf. 不过，我还没有找到使用它的好例子。（如果其他人找到了，请随时将其编辑到此答案中）。
You might be interested in seeing information about the difference between QString::sprintfand QString::arg.
你可能会希望看到有关的信息之间的区别QString::sprintf和QString::arg。
