SGI上的一个 map 的程序例子

最新推荐文章于 2022-05-23 20:39:37 发布

blade2001

最新推荐文章于 2022-05-23 20:39:37 发布

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分类专栏： C/C++ 文章标签： iterator struct

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本文通过一个具体的C++程序示例介绍了如何使用STL中的map容器，并展示了如何利用自定义比较器来实现字符串键值的排序，同时演示了如何遍历map并获取指定元素的前后项。

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Map has the important property that inserting a new element into a map does not invalidate iterators that point to existing elements. Erasing an element from a map also does not invalidate any iterators, except, of course, for iterators that actually point to the element that is being erased.

struct ltstr
{
bool operator()(const char* s1, const char* s2) const
{
return strcmp(s1, s2) < 0;
}
};

int main()
{
map<const char*, int, ltstr> months;

months["january"] = 31;
months["february"] = 28;
months["march"] = 31;
months["april"] = 30;
months["may"] = 31;
months["june"] = 30;
months["july"] = 31;
months["august"] = 31;
months["september"] = 30;
months["october"] = 31;
months["november"] = 30;
months["december"] = 31;

cout << "june -> " << months["june"] << endl;
map<const char*, int, ltstr>::iterator cur = months.find("june");
map<const char*, int, ltstr>::iterator prev = cur;
map<const char*, int, ltstr>::iterator next = cur;
++next;
--prev;
cout << "Previous (in alphabetical order) is " << (*prev).first << endl;
cout << "Next (in alphabetical order) is " << (*next).first << endl;
}