问题描述
我想为Qt标签格式化一个字符串，我在Qt上用C ++编程。
I'd like to format a string for Qt label, I'm programming in C++ on Qt.
在ObjC中我会写如下：
In ObjC I would write something like:
NSString *format=[NSString stringWithFormat: ... ];
如何在Qt中执行类似操作？
How to do something like that in Qt?
推荐答案
您可以像这样使用QString.arg
You can use QString.arg like this
QString my_formatted_string = QString("%1/%2-%3.txt").arg("~", "Tom", "Jane");
// You get "~/Tom-Jane.txt"
因为：
更改字符串的位置，而不必更改替换的顺序，例如
Changing the position of the string without having to change the ordering of substitution, e.g.
// To get "~/Jane-Tom.txt"
QString my_formatted_string = QString("%1/%3-%2.txt").arg("~", "Tom", "Jane");
或者，更改参数的类型不需要更改格式字符串，例如
Or, changing the type of the arguments doesn't require changing the format string, e.g.
// To get "~/Tom-1.txt"
QString my_formatted_string = QString("%1/%2-%3.txt").arg("~", "Tom", QString::number(1));
正如你所看到的，变化是最小的。当然，你通常不需要关心传递到QString :: arg（）的类型，因为大多数类型正确重载。
As you can see, the change is minimal. Of course, you generally do not need to care about the type that is passed into QString::arg() since most types are correctly overloaded.
一个缺点：QString :: arg（）不处理std :: string。你需要在你的std :: string上调用：QString :: fromStdString（），使它成为一个QString，然后传递给QString :: arg（）。尝试将使用QString的类与使用std :: string的类分开。
One drawback though: QString::arg() doesn't handle std::string. You will need to call: QString::fromStdString() on your std::string to make it into a QString before passing it to QString::arg(). Try to separate the classes that use QString from the classes that use std::string. Or if you can, switch to QString altogether.
更新：例子由Frank Osterfeld更新。
UPDATE: Examples are updated thanks to Frank Osterfeld.
更新：示例更新感谢alexisdm。
UPDATE: Examples are updated thanks to alexisdm.
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