求500-800之间奇数的和值，偶数的平均值.运用计算机c++解题

这个程序才是对的，可以运行的
#include<iostream>
using namespace std;
int sum;
float everage;
int i,j;
float get_even_everage()
{ j=0;
for(i=500;i<=800;i=i+2)
{

everage=everage+i;
j++;
}
return everage/j;
}
int get_odd_sum()
{
for(i=501;i<=700;i=i+2)
sum=sum+i;
return sum;
}
int main()
{
cout<<"奇数的和是："<<get_odd_sum()<<endl;
cout<<"偶数的平均值是："<<get_even_everage()<<endl;
return 0;
}

#include<iostream>
using namespace std;
int sum;
float everage;
int i,j;
float get_even_everage()
{
for(i=500;i<=800;i+2)
{
everage=everage+i;
j++;
return everage/j;
}
int get_odd_sum()
{
for(i=501;i<=700;i+2)
sum=sum+i;
return sum;
}
int main()
{
cout<<"奇数的和