C++ all_of, any_of, none_of

C++11 新增了 Haskell 的类似语句。

https://hackage.haskell.org/package/base-4.15.0.0/docs/Data-List.html

如果你忘了 Foldable 是啥，看看 Tim 的笔记。类似 Iterator 。

https://tgdwyer.github.io/haskell4/

• Foldabale , 可以通过 iterator 然后 reduce 成一个单一值
• Iterator, 基本和 Foldable 类似，但是 Iterator 功能更强大，不止弄成单一值。。。

用法看

std::all_of, std::any_of, std::none_of - cppreference.com

例子

读取 vector of vector 中的所有值。

#include <vector>
#include <iostream>
#include <algorithm>
#include <numeric>

int main(){
    std::vector<std::vector<int>> agents;

    agents.push_back(std::vector<int>(10));
    // ivec will become: [0..9] 
    std::iota(agents[agents.size()-1].begin(), agents[agents.size()-1].end(), 0); 

    agents.push_back(std::vector<int>(5));
    // ivec will become: [0..4] 
    std::iota(agents[agents.size()-1].begin(), agents[agents.size()-1].end(), 0); 

    agents.push_back(std::vector<int>(8));
    // ivec will become: [0..7] 
    std::iota(agents[agents.size()-1].begin(), agents[agents.size()-1].end(), 0);
    
    // print all elements....
    unsigned int i = 0; 
    while (std::any_of(agents.begin(), agents.end(), [i](const std::vector<int>& v){ return i < v.size(); }))
    {   
        std::cout << "i = " << i << " \n"; 
        for (unsigned int k = 0; k < agents.size(); k++){
            if (i < agents[k].size()){
                std::cout << "agent "<< i << " : "<< agents[k][i] << "\n"; 
            }else
            {
                std::cout << "agent "<< i << " : None\n"; 
            }
            
            
        }
        std::cout << "----------------------------\n"; 
        i++; 
    }
    std::cout << "The maximum length over all three vectors " << i << std::endl;  


}