好吧基本上我需要使用std :: transform()函数。我正在尝试将对象函数作为最后一个参数传递,但它似乎无法工作。
class isprime {
public:
// declares the constructor and the operator() overloading
isprime(){ number = 0, primes.push_back(2);};
bool operator()(int);
private:
// various private functions and variables
int number;
list<int> primes; //creats a list via the stl library
void morePrimes(int); //function to generate more prime numbers
bool it; // Iterator for the morePrimes list
bool primeCheck; // Bool used in the morePrimes function
};
bool isprime::operator()(int number)
{
if(number == 1) //returns false for 1
return false;
if(number > primes.back()){ //Tests to see if the list of primes range would include the number, if not it runs the morePrimes function
morePrimes(number);
}
it = binary_search(primes.begin(),primes.end(),number); //uses stl find to see if the number is in the list of primes.
if(it) //if the returned iterator points to a value = to number then number is prim.
return true;
return false; //returns false if the number wasnt found
};
transform(random_list.begin(), random_list.end(), isprime_list.begin(), test());
上面我已经包含了用于转换的类,函数和调用。任何人都知道为什么这不起作用?我无法弄明白。
答案 0 :(得分:0)
如果您在某处提供void isprime::more_primes(int)
,则删除test()
中的括号可能就足够了:
int main()
{
auto gen = bind(uniform_int_distribution<>(), mt19937());
list<int> random_list;
for (int i=0; i<5; i++) random_list.push_back(gen());
list<int> isprime_list(random_list.size());
isprime test;
transform(random_list.begin(), random_list.end(), isprime_list.begin(), test);
}
在Coliru上看到它“正在运行”(好吧,编译):http://coliru.stacked-crooked.com/a/3d908cb5cdc5c543
#include <list>
#include <algorithm>
using namespace std;
class isprime {
public:
// declares the constructor and the operator() overloading
isprime(){ number = 0, primes.push_back(2);};
bool operator()(int);
private:
// various private functions and variables
int number;
list<int> primes; // creats a list via the stl library
void morePrimes(int); // function to generate more prime numbers
bool it; // Iterator for the morePrimes list
bool primeCheck; // Bool used in the morePrimes function
};
bool isprime::operator()(int number)
{
if(number == 1) // returns false for 1
return false;
if(number > primes.back()){ // Tests to see if the list of primes range would include the number, if not it runs the morePrimes function
morePrimes(number);
}
it = binary_search(primes.begin(),primes.end(),number); // uses stl find to see if the number is in the list of primes.
if(it) // if the returned iterator points to a value = to number then number is prim.
return true;
return false; // returns false if the number wasnt found
}
void isprime::morePrimes(int) {}
#include <random>
#include <functional>
#include <iostream>
#include <iterator>
int main()
{
auto gen = bind(uniform_int_distribution<>(), mt19937());
list<int> random_list;
for (int i=0; i<5; i++) random_list.push_back(gen());
list<int> isprime_list(random_list.size());
isprime test;
transform(random_list.begin(), random_list.end(), isprime_list.begin(), test);
}