C++ 用一个整数连接两个 QStrings
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Concatenating two QStrings with an integer
提问by Karim M. El Tel
I want to do something like this in C++ using Qt:
我想在 C++ 中使用 Qt 做这样的事情：
int i = 5;
QString directory = ":/karim/pic" + i + ".jpg";
where +means I want to concatenate the strings and the integer (that is, directoryshould be :/karim/pic5.jpg). How can I do this?
where+表示我想连接字符串和整数（即directory应该是:/karim/pic5.jpg）。我怎样才能做到这一点？
回答by Sebastian Negraszus
回答by Cubbi
(EDIT: this is an answer to the question before the edit that mentioned QString. For QString, see the newer answer)
（编辑：这是对提到 QString 的编辑之前问题的答案。对于 QString，请参阅较新的答案）
This can be done as a very similar one-liner using C++11:
这可以使用C++11以非常相似的单行方式完成：
int i = 5;
std::string directory = ":/karim/pic" + std::to_string(i) + ".jpg";
Test: https://ideone.com/jIAxE
With older compilers, it can be substituted with Boost:
对于较旧的编译器，它可以用Boost代替：
int i = 5;
std::string directory = ":/karim/pic" + boost::lexical_cast<std::string>(i) + ".jpg";
Test: https://ideone.com/LFtt7
But the classic way to do it is with a string stream object.
但经典的方法是使用字符串流对象。
int i = 5;
std::ostringstream oss;
oss << ":/karim/pic" << i << ".jpg";
std::string directory = oss.str();
Test: https://ideone.com/6QVPv
回答by Jens Luedicke
Have a look at stringstream:
看看字符串流：
http://cplusplus.com/reference/iostream/stringstream/
http://cplusplus.com/reference/iostream/stringstream/
ostringstream oss(ostringstream::out);
oss << ":/karim/pic";
oss << i
oss << ".jpg";
cout << oss.str();
回答by Tobias Schlegel
#include <sstream>
#include <string>
int i = 5;
std::stringstream s;
s << ":/karim/pic" << i << ".jpg";
std::string directory = s.str();
