题解 | #1-n之间偶数之和#

//使用while循环

#include using namespace std;

int main() {

int n;
cin >> n;
int sum = 0;
//先获取1-n之间的所有偶数，然后再依次相加1.先判断是否是偶数，然后再相加
int i=0;
while(i<=n)
{
    if(i%2==0)
    {
        sum+=i;
    }
    i++;
}



cout << sum << endl;

return 0;

} //do while循环 #include using namespace std;

int main() {

int n;
cin >> n;
int sum = 0;
int i=0;

do { if(i%2==0) { sum+=i;
} i++; } while(i<=n);

cout << sum << endl;

return 0;

} //for 循环 #include using namespace std;

int main() {

int n;
cin >> n;
int sum = 0;
for(int i=0;i<=n;i++)
{
    if(i%2==0)
    {
        sum+=i;
    }
}



cout << sum << endl;

return 0;

}