error: ld returned 1 exit status 和 error:undefined reference

undefined reference

往往是链接时出现错误，无法解析引用。这篇文章总结的很好undefined reference问题总结

error: ld returned 1 exit status

链接文件没有建立

案例

 #include<vector>

 #include<algorithm>

 #include<iostream>

 #include<cstdio>

 using namespace std;

 class Solution {

     static int** nv;

     static bool cmp(int x, int y){

         int lenx = nv[x][];

         int leny = nv[y][];

         for(int xi = lenx-, yi = leny-; xi > , yi > ; xi--, yi--){

             if(nv[x][xi] < nv[y][yi]) return true;

             if(nv[x][xi] > nv[y][yi]) return false;

         }

         return false;

     }

 public:

     vector<int> lexicalOrder(int n) {

         nv = new int* [n+];

         for(int i = ; i < n+; i++){

             nv[i] = new int[];

         }

         for(int i = ; i <= n; i ++){

             int y = i;

             int yi = ;

             while(y != ){

                 nv[i][yi++] = y % ;

                 y = y / ;

             }

             nv[i][] = yi;

         }

         vector<int> v;

         for(int i = ; i <= n; i ++){

             v.push_back(i);

         }

         sort(v.begin(), v.end(), cmp);

         return v;

     }

     // vector<int> lexicalOrderList(int start, int last, int s, int n, vector<int>& v){

     // }

 };

 int main(){

     Solution s;

     vector<int> v = s.lexicalOrder();

     for(int i = ; i < v.size(); i ++){

         cout << v[i] << " ";

     }

     cout << endl;

     return ;

 }