how to change this few code into C programming?(from C++)

Code:

---

#include <cstdio>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
  int T;
  scanf("%d", &T);
  while (T--) {
    int M, N, num[30000];
    scanf("%d%d", &M, &N);
    for (int i = 0; i < M; i++) {
      scanf("%d", &num[i]);
    }
    vector<int> box;
    int done = 0, need = 0;
    while (N--) {
      int index;
      scanf("%d", &index);
      while (box.size() < index) {
        vector<int>::iterator it = lower_bound(box.begin(), box.end(), num[done]);
        box.insert(it, num[done++]);
      }
      printf("%d\n", box[need++]);
    }
    if (T) {
      puts("");
    }
  }
  return 0;
}

---

You mean this broken hybridization of C++/C code into just C? How about you tell us what you are trying to do and then make an attempt. Looking for answers to homework problems on the internet and then just dumping what you find on a forum in hopes that someone else will do work for you is not good practice nor will it get you help here. You should forget this code, start from scratch, beginning with defining your problem. Then read about the development process