Question

求助、求助 c语言 编程求2+4+6+8+......n n值从键盘输入 谢谢大侠们

Answer 1

#include <stdio.h>
int main ( )
{
int i,j,sum;
sum=0;
printf("请输入一个整偶数！\n");
scanf("%d",&j);
for(i=2;i<=j;i+=2)
{
sum=sum+i;
}
printf("sum=%d\n",sum);
return 0;
}

Answer 2

#include<stdio.h>
void main()
{
int s=0,n=0,i;
printf("press n=");
scanf("%d",&n);
for(i=2;i<=n;i+=2)
s+=i;
printf("%d\n",s);
}

Answer 3

int main()
{
int n = 0;
int i = 0;
int sum = 0;
scanf("%d", &n);
for (i=2; i<=n; i+=2)
{
sum += i;
}
printf("%d\n", sum);
system("pause");
return 0;
}

Answer 4

int main()
{
int n,sum;
scanf("%d", &n);
sum=n;
while((n=n-2)>=0)
sum+=n;
printf("%d",sum);
getchar();
}