本文介绍了如何在 C++ 中反向迭代地图?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
I'm having trouble iterating in reverse over a map in GCC C++. When I use a reverse iterator, it seems I can't assign anything to it - the compiler complains. I'm working around it with some awkward code using a forward iterator, but it's not very elegant. Any thoughts?
解决方案
Here's an example of iterating backward through a std::map:
#include <iostream>
#include <map>
#include <string>
int main() {
std::map<std::string, std::string> m;
m["a"] = "1";
m["b"] = "2";
m["c"] = "3";
for (auto iter = m.rbegin(); iter != m.rend(); ++iter) {
std::cout << iter->first << ": " << iter->second << std::endl;
}
}
If you are pre-C++11, you'll just need to spell out auto, which is:
std::map<std::string, std::string>::reverse_iterator
Note that if you're using boost, you can use a range-based for loop with a reverse adapter:
#include <boost/range/adaptor/reversed.hpp>
for (auto& iter : boost::adaptors::reverse(m)) {
std::cout << iter.first << ": " << iter.second << std::endl;
}
这篇关于如何在 C++ 中反向迭代地图?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！
本站部分内容来源互联网,如果有图片或者内容侵犯您的权益请联系我们删除！