1^2+2^2+3^2+…+n^2的值 dowhile-dowhile.cpp

我正在学习C编程

#include<stdio.h>   /**/
void main()
{
	printf("\n\t求1^2+2^2+…+n^2(n<1时结束)的值 while-while\n\n");
	do
	{int n;
	printf("\n  输入n的值: ");
	scanf("%d",&n);
	if(n<1){break;}
	int i=1;
	unsigned long j,sum=0;
	do{j=i*i; sum+=j; i++;}while(i<=n);
    if(n==1)printf("  1^2=%u\n",sum);
	else if(n==2)printf("  1^2+2^2=%u\n",sum);
		 else if(n==3)printf("  1^2+2^2+3^2=%u\n",sum);
			  else printf("  1^2+2^2+…+%d^2=%lu\n",n,sum);
	}while(1);
}