问我需要知道如何使用c++中的某个增量值来添加

EN

#include <iostream>

using namespace std;

int main(){
  //while loop sum
  int sumw = 0;
  //for loop sum
  int sumf = 0;
  //starting integer
  int nums;
  //ending integer
  int nume;
  //increment integer
  int numi;

  cout <<"Please enter a starting value: " << endl;
  cin >> nums;
  cout <<"Please enter an ending value: " << endl;
  cin >> nume;
  cout <<"Please enter a positive increment value: " << endl;
  cin >> numi;

  if (numi <= 0 || nums > nume) cout << "Error ";
  if (numi <= 0 || nums > nume) return 0;

  for (int i = 1; i <= numi; i++){      
    sumf =+ numi;
  }
  cout << "Sum(using for loop): " << sumf;

  return 0;
}