C++ 如何在std::binary\u搜索中设置针类型
我有以下简单的程序,可以搜索一个项目:C++ 如何在std::binary\u搜索中设置针类型,c++,algorithm,search,C++,Algorithm,Search,我有以下简单的程序,可以搜索一个项目: #include <vector> #include <algorithm> #include <string> #include <iostream> class Record { public: Record() = default; Record(std::string name, int data) : mName(name), mData(data) { } std::st
#include <vector>
#include <algorithm>
#include <string>
#include <iostream>
class Record
{
public:
Record() = default;
Record(std::string name, int data) : mName(name), mData(data) { }
std::string mName;
int mData = 0;
};
int main(int, char**)
{
std::vector<Record> recs;
recs.emplace_back(Record("1", 1));
recs.emplace_back(Record("55555", 2));
recs.emplace_back(Record("333", 3));
recs.emplace_back(Record("qwertyuiop", 4));
recs.emplace_back(Record("22", 5));
recs.emplace_back(Record("4444", 6));
std::cout << "Unsorted:" << std::endl;
for (auto& rec : recs)
{
std::cout << "Name: " << rec.mName << " Data: " << rec.mData << std::endl;
}
std::cout << std::endl;
std::stable_sort(recs.begin(), recs.end(), [](const Record& lhs, const Record& rhs) -> bool
{
return lhs.mName.length() < rhs.mName.length();
});
std::cout << "Sorted:" << std::endl;
for (auto& rec : recs)
{
std::cout << "Name: " << rec.mName << " Data: " << rec.mData << std::endl;
}
std::cout << std::endl;
if (std::binary_search(
recs.begin(),
recs.end(),
Record("qwertyuiop", 4),
[](const Record& lhs, const Record& rhs) -> bool
{
return lhs.mName < rhs.mName;
}))
{
std::cout << "Found" << std::endl;
}
else
{
std::cout << "Not found" << std::endl;
}
return 0;
}
#包括
#包括
#包括
#包括
课堂记录
{
公众:
记录()=默认值;
记录(std::string name,int data):mName(name),mData(data){}
std::字符串mName;
int-mData=0;
};
int main(int,char**)
{
std::矢量记录;
记录安放(记录(“1”,1));
记录安置(记录(“55555”,2));
记录安置(记录(“333”,3));
记录安置(记录(“qwertyuiop”,4));
记录安置(记录(“22”,5));
记录安放(记录(“4444”,6));
std::cout您可以通过添加一个隐式
构造函数将std::string
转换为Record
,并添加一个操作符将Record
转换为std::string
operator std::string() const {
return mName;
}
Record(std::string name) : mName(name), mData(int()) {}
或者,您可以将现有构造函数转换为
Record(std::string name, int data = int()) : mName(name), mData(data) {}
但无论如何,您需要创建一个std::string
对象来进行搜索
/// create std::string object from "qwertyuiop"
if (std::binary_search(recs.begin(), recs.end(), std::string("qwertyuiop"),
[](const Record & lhs, const std::string & rhs) -> bool
{
return lhs.mName < rhs; /// rhs is a std::string type
})) {
std::cout << "Found" << std::endl;
}
else {
std::cout << "Not found" << std::endl;
}
///从“qwertyuiop”创建std::string对象
如果(std::binary_search(recs.begin()、recs.end()、std::string(“qwertyuiop”),
[](常量记录和lhs,常量标准::字符串和rhs)->bool
{
返回lhs.mName std::cout您可以创建处理异构比较的函数对象类型:
struct comp_t
{
bool operator()(Record const& lhs, std::string const& rhs) const {
return lhs.mName < rhs;
}
bool operator()(std::string const& lhs, Record const& rhs) const {
return lhs < rhs.mName;
}
};
我想不出用标准库实现这一点的方法,我会自己实现二进制搜索——大约10行代码
struct comp_t
{
bool operator()(Record const& lhs, std::string const& rhs) const {
return lhs.mName < rhs;
}
bool operator()(std::string const& lhs, Record const& rhs) const {
return lhs < rhs.mName;
}
};
std::binary_search(recs.begin(), recs.end(),
std::string("qwertyuiop"),
comp_t{})