在矢量上使用来自算法的查找函数
using the find function from algorithm on vector
我想在向量对象上使用算法库中的查找函数。向量对象是客户的向量，（客户是我做的类）。我首先运行它，它在stl_algo.h中给了我一个错误。我在网上搜索它，我也在这里搜索它，我在这里找到了一个关于它的问题，我运行了相同的代码，但我仍然收到那个错误。
我的代码在这里：
头文件：
#include <string>
#include <sstream>
#include <map>
#include <vector>
using namespace std;
enum Status {ACTIVE, INACTIVE};
class Customer {
private:
// ID Database class for storing customers' ids
class IdDB {
private:
friend class Customer;
// member field
static map <string, int> idList;
// member function
static int getNumber (const string &threeLetters) {
map<string, int>::iterator i = idList.find(threeLetters);
if (i == idList.end()) {
idList.insert(pair <string, int> (threeLetters, 0));
return 0;
}else{
return ++(i->second);
}
}
};
string id;
string name;
string address;
Status status;
void makeId () {
string threeLetters = name.substr(0, 3);
int idNum = IdDB::getNumber(threeLetters);
stringstream oss;
oss << threeLetters << idNum;
id = oss.str();
}
public:
Customer (const string&, const string&, const Status);
// Accessor Methods
string &getId ();
string &getName ();
string &getAddress ();
Status getStatus ();
// Mutator Methods
void setAddress (const string&);
void setStatus (const Status);
// Misc. Methods
void printStatus ();
// Equality Operator Overloading
friend bool operator == (Customer&, Customer&);
};
class CustomerDB {
private:
static vector<Customer> customersList;
public:
static void addCustomer (const Customer&);
static void deleteCustomer (Customer&);
};
源代码：
#include <iostream>
#include <string>
#include <algorithm>
#include "Customer.h"
using namespace std;
map<string, int> Customer::IdDB::idList;
Customer::Customer (const string &cName, const string &cAddress, const Status cStatus) : name(cName), address(cAddress), status(cStatus) {
makeId();
}
// Accessor Methods
string &Customer::getId () { return id; }
string &Customer::getName () { return name; }
string &Customer::getAddress () { return address; }
Status Customer::getStatus () { return status; }
// Mutator Methods
void Customer::setAddress (const string &newAddress) { address = newAddress; }
void Customer::setStatus (const Status newStatus) { status = newStatus; }
// Misc. Methods
void Customer::printStatus () {
if (status == ACTIVE)
cout << "Active";
else
cout << "In-Active";
}
vector<Customer> CustomerDB::customersList;
void CustomerDB::addCustomer (const Customer &customer) {
customersList.push_back(customer);
}
void CustomerDB::deleteCustomer (Customer &customer) {
vector<Customer>::iterator i;
i = find(customersList.begin(), customersList.end(), customer); // getting error in here
}
// Equality Operator Overloading
bool operator == (Customer &cust1, Customer &cust2) {
return cust1.getId() == cust2.getId();
}
使用 Code：：Blocks 构建后，我得到了这个，
在头文件 stl_algo.h 中：
}
/// This is an overload used by find() for the RAI case.
template<typename _RandomAccessIterator, typename _Tp>
_RandomAccessIterator
__find(_RandomAccessIterator __first, _RandomAccessIterator __last,
const _Tp& __val, random_access_iterator_tag)
{
typename iterator_traits<_RandomAccessIterator>::difference_type
__trip_count = (__last - __first) >> 2;
for (; __trip_count > 0; --__trip_count)
{
if (*__first == __val) // error in here exactly getting a red block
return __first;
++__first;
if (*__first == __val)
return __first;
++__first;
if (*__first == __val)
return __first;
谢谢
编辑：这是构建日志
Compiling: C:UsersKiKo-SaMaDesktopC++DVD_AppCustomer.cpp
In file included from c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/algorithm:63:0,
from C:UsersKiKo-SaMaDesktopC++DVD_AppCustomer.cpp:5:
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h: In function '_RandomAccessIterator std::__find(_RandomAccessIterator, _RandomAccessIterator, const _Tp&, std::random_access_iterator_tag) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<Customer*, std::vector<Customer> >, _Tp = Customer]':
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h:4403:45: instantiated from '_IIter std::find(_IIter, _IIter, const _Tp&) [with _IIter = __gnu_cxx::__normal_iterator<Customer*, std::vector<Customer> >, _Tp = Customer]'
C:UsersKiKo-SaMaDesktopC++DVD_AppCustomer.cpp:42:66: instantiated from here
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h:162:4: error: no match for 'operator==' in '__first.__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = Customer*, _Container = std::vector<Customer>, __gnu_cxx::__normal_iterator<_Iterator, _Container>::reference = Customer&]() == __val'
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h:162:4: note: candidates are:
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/postypes.h:218:5: note: template<class _StateT> bool std::operator==(const std::fpos<_StateT>&, const std::fpos<_StateT>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_pair.h:201:5: note: template<class _T1, class _T2> bool std::operator==(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_iterator.h:285:5: note: template<class _Iterator> bool std::operator==(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_iterator.h:335:5: note: template<class _IteratorL, class _IteratorR> bool std::operator==(const std::reverse_iterator<_IteratorL>&, const std::reverse_iterator<_IteratorR>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/allocator.h:122:5: note: template<class _T1, class _T2> bool std::operator==(const std::allocator<_T1>&, const std::allocator<_T2>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/allocator.h:127:5: note: template<class _Tp> bool std::operator==(const std::allocator<_Tp1>&, const std::allocator<_Tp1>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/basic_string.h:2427:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const std::basic_string<_CharT, _Traits, _Alloc>&, const std::basic_string<_CharT, _Traits, _Alloc>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/basic_string.h:2434:5: note: template<class _CharT> typename __gnu_cxx::__enable_if<std::__is_char<_Tp>::__value, bool>::__type std::operator==(const std::basic_string<_CharT>&, const std::basic_string<_CharT>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/basic_string.h:2448:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const _CharT*, const std::basic_string<_CharT, _Traits, _Alloc>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/basic_string.h:2460:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const std::basic_string<_CharT, _Traits, _Alloc>&, const _CharT*)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/streambuf_iterator.h:194:5: note: template<class _CharT, class _Traits> bool std::operator==(const std::istreambuf_iterator<_CharT, _Traits>&, const std::istreambuf_iterator<_CharT, _Traits>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_tree.h:309:5: note: template<class _Val> bool std::operator==(const std::_Rb_tree_iterator<_Tp>&, const std::_Rb_tree_const_iterator<_Val>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_tree.h:846:5: note: template<class _Key, class _Val, class _KeyOfValue, class _Compare, class _Alloc> bool std::operator==(const std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>&, const std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_map.h:877:5: note: template<class _Key, class _Tp, class _Compare, class _Alloc> bool std::operator==(const std::map<_Key, _Tp, _Compare, _Alloc>&, const std::map<_Key, _Tp, _Compare, _Alloc>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_multimap.h:795:5: note: template<class _Key, class _Tp, class _Compare, class _Alloc> bool std::operator==(const std::multimap<_Key, _Tp, _Compare, _Alloc>&, const std::multimap<_Key, _Tp, _Compare, _Alloc>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_vector.h:1273:5: note: template<class _Tp, class _Alloc> bool std::operator==(const std::vector<_Tp, _Alloc>&, const std::vector<_Tp, _Alloc>&)
C:UsersKiKo-SaMaDesktopC++DVD_AppCustomer.cpp:46:6: note: bool operator==(Customer&, Customer&)
C:UsersKiKo-SaMaDesktopC++DVD_AppCustomer.cpp:46:6: note: no known conversion for argument 2 from 'const Customer' to 'Customer&'
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h:4403:45: instantiated from '_IIter std::find(_IIter, _IIter, const _Tp&) [with _IIter = __gnu_cxx::__normal_iterator<Customer*, std::vector<Customer> >, _Tp = Customer]'
C:UsersKiKo-SaMaDesktopC++DVD_AppCustomer.cpp:42:66: instantiated from here
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h:166:4: error: no match for 'operator==' in '__first.__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = Customer*, _Container = std::vector<Customer>, __gnu_cxx::__normal_iterator<_Iterator, _Container>::reference = Customer&]() == __val'
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h:166:4: note: candidates are:
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/postypes.h:218:5: note: template<class _StateT> bool std::operator==(const std::fpos<_StateT>&, const std::fpos<_StateT>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_pair.h:201:5: note: template<class _T1, class _T2> bool std::operator==(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_iterator.h:285:5: note: template<class _Iterator> bool std::operator==(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_iterator.h:335:5: note: template<class _IteratorL, class _IteratorR> bool std::operator==(const std::reverse_iterator<_IteratorL>&, const std::reverse_iterator<_IteratorR>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/allocator.h:122:5: note: template<class _T1, class _T2> bool std::operator==(const std::allocator<_T1>&, const std::allocator<_T2>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/allocator.h:127:5: note: template<class _Tp> bool std::operator==(const std::allocator<_Tp1>&, const std::allocator<_Tp1>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/basic_string.h:2427:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const std::basic_string<_CharT, _Traits, _Alloc>&, const std::basic_string<_CharT, _Traits, _Alloc>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/basic_string.h:2434:5: note: template<class _CharT> typename __gnu_cxx::__enable_if<std::__is_char<_Tp>::__value, bool>::__type std::operator==(const std::basic_string<_CharT>&, const std::basic_string<_CharT>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/basic_string.h:2448:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const _CharT*, const std::basic_string<_CharT, _Traits, _Alloc>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/basic_string.h:2460:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const std::basic_string<_CharT, _Traits, _Alloc>&, const _CharT*)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/streambuf_iterator.h:194:5: note: template<class _CharT, class _Traits> bool std::operator==(const std::istreambuf_iterator<_CharT, _Traits>&, const std::istreambuf_iterator<_CharT, _Traits>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_tree.h:309:5: note: template<class _Val> bool std::operator==(const std::_Rb_tree_iterator<_Tp>&, const std::_Rb_tree_const_iterator<_Val>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_tree.h:846:5: note: template<class _Key, class _Val, class _KeyOfValue, class _Compare, class _Alloc> bool std::operator==(const std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>&, const std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_map.h:877:5: note: template<class _Key, class _Tp, class _Compare, class _Alloc> bool std::operator==(const std::map<_Key, _Tp, _Compare, _Alloc>&, const std::map<_Key, _Tp, _Compare, _Alloc>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_multimap.h:795:5: note: template<class _Key, class _Tp, class _Compare, class _Alloc> bool std::operator==(const std::multimap<_Key, _Tp, _Compare, _Alloc>&, const std::multimap<_Key, _Tp, _Compare, _Alloc>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_vector.h:1273:5: note: template<class _Tp, class _Alloc> bool std::operator==(const std::vector<_Tp, _Alloc>&, const std::vector<_Tp, _Alloc>&)
C:UsersKiKo-SaMaDesktopC++DVD_AppCustomer.cpp:46:6: note: bool operator==(Customer&, Customer&)
C:UsersKiKo-SaMaDesktopC++DVD_AppCustomer.cpp:46:6: note: no known conversion for argument 2 from 'const Customer' to 'Customer&'
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h:170:4: error: no match for 'operator==' in '__first.__gnu_cxx::__normal_iterator<_Iterator, _Container>::operator* [with _Iterator = Customer*, _Container = std::vector<Customer>, __gnu_cxx::__normal_iterator<_Iterator, _Container>::reference = Customer&]() == __val'
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_algo.h:170:4: note: candidates are:
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/postypes.h:218:5: note: template<class _StateT> bool std::operator==(const std::fpos<_StateT>&, const std::fpos<_StateT>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_pair.h:201:5: note: template<class _T1, class _T2> bool std::operator==(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_iterator.h:285:5: note: template<class _Iterator> bool std::operator==(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/stl_iterator.h:335:5: note: template<class _IteratorL, class _IteratorR> bool std::operator==(const std::reverse_iterator<_IteratorL>&, const std::reverse_iterator<_IteratorR>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/allocator.h:122:5: note: template<class _T1, class _T2> bool std::operator==(const std::allocator<_T1>&, const std::allocator<_T2>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/allocator.h:127:5: note: template<class _Tp> bool std::operator==(const std::allocator<_Tp1>&, const std::allocator<_Tp1>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/basic_string.h:2427:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator==(const std::basic_string<_CharT, _Traits, _Alloc>&, const std::basic_string<_CharT, _Traits, _Alloc>&)
c:mingwbin../lib/gcc/mingw32/4.6.2/include/c++/bits/basic_string.h:2434:5: note: template<class _CharT> typename __gnu_cxx::__enable_if<std::__is_char<_Tp>::__value, bool>::__type std::operator==(const std::basic_string<_CharT>&, const std::basic_string<_CharT>&)
Process terminated with status 1 (0 minutes, 1 seconds)
50 errors, 0 warnings
你应该研究你的常量正确性，问题是你的相等比较器通过非常量引用获取参数，但find的最后一个参数是通过const引用获取的，这意味着编译器不能在那里使用它。
顺便说一下，一旦您在那里添加了const，您将被迫向数据添加const访问器。此外，如果您的运算符仅使用公共接口，则无需将其声明为 friend
CodeBlocks 可能会给出有关 stl 文件的错误，但它们实际上不是错误。它显示错误的相关 stl 文件。
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