我不明白爲什麼for循環無法在此代碼上工作

Question

我想使矢量（mycount）指示myvec中元素的頻率。你能讓我知道什麼是錯的嗎？

#include <iostream> 
#include <vector> 
#include <cstdlib> 
#include <functional> 
#include <algorithm> 
using namespace std; 

int main() { 
    int num; 

    cout << "How many numbers do you want to read in?" << endl; 
    cin >> num; 


    vector<int> myvec(num); 

    std::generate(myvec.begin(), myvec.end(), []()->int {return rand(); }); 

    for (int i = 0; i < num; ++i) { 
    vector<int> mycount[i] = count(myvec.begin(), myvec.end(), myvec[i]); 
     cout << mycount[i] << endl; 
    } 

    return 0; 
} 

Answer 1

我懷疑你的意思是使用：

vector<int> myvec(num); 

// Create a vector for storing the counts as well. 
vector<int> mycount(num); 

std::generate(myvec.begin(), myvec.end(), []()->int {return rand(); }); 

for (int i = 0; i < num; ++i) { 

    // Get the counts of the element at this index and store it. 
    mycount[i] = count(myvec.begin(), myvec.end(), myvec[i]); 

    cout << mycount[i] << endl; 
} 

Answer 2

你的mycount定義是錯誤的。檢查下面的代碼

#include <iostream> 
#include <vector> 
#include <cstdlib> 
#include <functional> 
#include <algorithm> 
using namespace std; 

int main() { 
    int num; 

    cout << "How many numbers do you want to read in?" << endl; 
    cin >> num; 


    vector<int> myvec(num); 

    std::generate(myvec.begin(), myvec.end(), []()->int {return rand(); }); 

    vector<int> mycount(num); \\declare mycount with num elements 

    for (int i = 0; i < num; ++i) { 
    \\populate the counter for each element 
    mycount[i] = count(myvec.begin(), myvec.end(), myvec[i]); 
     cout << mycount[i] << endl; 
    } 

    return 0; 
}