通過迭代器插入元素C++

Question

我試圖插入元素設置「教師」。教師是結構，學校的一部分。學校結構在另一個叫做城鎮的地方。我試圖把老師「綠色」放到學校裏，「布朗」是校長。我用find來找到學校，但我不能讓他進來。運營商<，==被定義爲比較校長。

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 

編輯..錯誤

|| === ulohaa1，調試=== | /home/ulohaa1/main.cpp||在函數'布爾變換（常量字符*，常量字符*）'：| /home/ulohaa1/main.cpp|84|錯誤：沒有匹配函數調用'std :: set> :: insert（std :: string &）const'| /home/michal/Desktop/prog/ulohaa1/main.cpp|84|note：考生是：| /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|note：對於隱式'this'參數從'const std :: set>'到'std :: set>'|沒有已知的轉換。 /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 =性病:: basic_string的] | /usr/include/c++/4.6/bits/stl_set.h|444|note：候選人需要2個參數，1個提供| /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>] | || ===構建完成：7個錯誤，0個警告=== |

THX您的幫助球員

Answer 1

你有編譯器錯誤提示你沒有重載operator <爲您的學校類型：

#include <set> 
#include <string> 

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

如果你需要更新你所需要的設定一所學校到

1）查找集合

2）如果發現該學校，該值保存到臨時學校

3）更新的臨時學校

4）刪除自定校，並插入臨時學校設定的

這是一組容器的性質。更新項目意味着使用更新的項目進行移除和插入。所以基本上這樣：

// 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是你的「全球」組。

編輯：如果使用圖（我認爲是上級），代碼可以是如此簡單：

#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"); 
}