通过迭代器插入元素c-Java 学习之路

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我试图将元素插入到“老师”中 . 教师是结构，学校的一部分 . 学校结构在另一个叫做城镇的地方 . 我想把老师“绿色”放到学校，“布朗”是校长 . 我用find找到了学校，但我无法让他进去 . 运营商<，==被定义为比较校长 .

bool operator<(const School& l, const School& r){
  return (l.headmaster) < (r.headmaster);
}
bool operator==(const School& l, const School& r){
  return (l.headmaster) == (r.headmaster);
}

struct School {
    string headmaster;
    set <string> teachers;
};

set<School>::iterator it;
set <School> town;
// now I alocated few schools and insert them into town, 
School *pSchool = new School(): // i will use pSchool to find school with brown as headmaster
pSchool > headmaster  = "Brown"; // 
it = rozvrh.find(*pSchool);
cout << it->headmaster // gives Brown
it->teachers.insert("Green"); /// error

编辑..错误

|| === ulohaa1，Debug === | /home/ulohaa1/main.cpp||在函数'bool transform（const char *，const char *）'中： /home/ulohaa1/main.cpp|84|error：没有匹配函数来调用'std :: set> :: insert（std :: string＆）const'| /home/michal/Desktop/prog/ulohaa1/main.cpp|84|note：候选人是：| / usr / include / c /4.6/bits/stl_set.h|407|note：std :: pair，_Compare，typename _Alloc :: rebind <_Key> :: other> :: const_iterator，bool> std :: set <_Key ，_Compare，_Alloc> :: insert（const value_type＆）[with _Key = std :: basic_string，Compare = std :: less>， Alloc = std :: allocator>，typename std :: _ Rb_tree <_Key，_Key，std :: _Identity <Key>， Compare，typename _Alloc :: rebind <_Key> :: other> :: const_iterator = std :: _ Rb_tree_const_iterator>，std :: set <_Key，_Compare，_Alloc> :: value_type = std :: basic_string] | / usr / include / c /4.6/bits/stl_set.h|407注：从'const std :: set>'到'std :: set>'的隐式'this'参数没有已知的转换/ usr / include / c /4.6/bits/stl_set.h|444|note：std :: set <_Key，_Compare，_Alloc> :: iterator std :: set <_Key，_Compare，_Alloc> :: insert（std：：set <_Key，_Compare，_Alloc> :: const_iterator，const value_type＆）[with _Key = std :: basic_string，Compare = std :: less>， Alloc = std :: allocator>，std :: set <_Key，_Compare， _Alloc> :: iterator = std :: _ Rb_tree_const_iterator>，std :: set <_Key，_Compare，_Alloc> :: const_iterator = std :: _ Rb_tree_const_iterator>，std :: set <_Key，_Compare，_Alloc> :: value_type = std：：basic_string的] | / usr / include / c /4.6/bits/stl_set.h|444注：候选人需要2个参数，1个提供| / usr / include / c /4.6/bits/stl_set.h|464|note：template void std :: set :: insert（_InputIterator，_InputIterator）[with _InputIterator = _InputIterator，_Key = std :: basic_string，Compare = std：：less>， Alloc = std :: allocator>] | || ===构建完成：7个错误，0个警告=== |

谢谢你的帮助

1 回答

您的编译器错误表明您没有为您的School类型重载operator <：

#include <set>
#include <string>

struct School
{
    std::string headmaster;
    std::set<std::string> teachers;
    bool operator<(const School& s) const { return headmaster < s.headmaster; }
};

如果您需要更新您需要的学校中的学校

1）找到集合中的学校

2）如果找到，将值保存到临时学校

3）更新临时学校

4）从集合中删除学校并将临时学校插入到集合中

这就是集合容器的本质 . 更新项目意味着删除并插入更新的项目 . 基本上这个：

// we will search for Mr Brown's school and add a teacher
School searchSchool;
searchSchool.headmaster = "Brown";
std::set<School>::iterator it = mainSchool.find(searchSchool);

// if found, add the teacher
if (it != mainSchool.end())
{
    // save the school
    School theSchool = *it;
    theSchool.teachers.insert("A new teacher");
    mainSchool.erase(it);
    mainSchool.insert(theSchool);
}

mainSchool是您的“全球”集 .

编辑：如果使用 Map （我认为是优越的），代码可以像这样简单：

#include <map>
#include <set>
#include <string>
typedef std::set<std::string> StringSet;
typedef std::map<std::string, StringSet>  SchoolMap;

using namespace std;
int main()
{
    SchoolMap allSchools;
    allSchools.insert(make_pair("Brown", StringSet()));
    allSchools.insert(make_pair("Smith", StringSet()));

    // search for Mr Brown's school
    SchoolMap::iterator it = allSchools.find("Brown");

    // if found, add the teacher
    if (it != allSchools.end())
    // save the teacher
        it->second.insert("A new teacher");
}

回复于 2024-05-14T10:19:11+08:00

通过迭代器插入元素c

1 回答

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