函数 求和 289.cpp

我正在学习C编程

/**/
#include<stdio.h>     //导入包含I/O函数的头文件stdio.h    

double addodd(int n)  //声明奇数和函数,返回双精度值
{
	double x,s=0.0;  int i;
	for(i=1;i<=n;i+=2){x=1/(double)i; s+=x;}
	return s;         //返回奇数和值回主调函数
}
double addeven(int n) //声明偶数和函数,返回双精度值
{
	double x,s=0.0;  int i;
	for(i=2;i<=n;i+=2){x=1/(double)i; s+=x;}
	return s;         //返回偶数和值回主调函数 
}

void main()
{
	while(1)
	{
		int n;   double sum;
		printf("\n\t输入一个正整数n（n＜＝0时结束）:   ");	scanf("%d",&n);
		if(n<=0){break;}
		if(n%2==0)
		{
			sum=addeven(n);
			if(n==2){printf("  1/2＝%.3f\n",sum);}
			else if(n==4) {printf("  1/2＋1/4＝%.3f\n",sum);}
			else if(n==6) {printf("  1/2＋1/4＋1/6＝%.3f\n",sum);}
			else if(n==8) {printf("  1/2＋1/4＋1/6＋1/8＝%.3f\n",sum);}
			else if(n==10){printf("  1/2＋1/4＋1/6＋1/8＋1/10＝%.3f\n",sum);}
			else if(n==12){printf("  1/2＋1/4＋1/6＋1/8＋1/10＋1/12＝%.3f\n",sum);}
			else {printf("  1/2＋1/4＋1/6＋1/8＋1/10＋……＋1/%d＝%.3f\n",n,sum);}
		}
		if(n%2!=0)
		{
			sum=addodd(n);
			if(n==1){printf("  1/1＝%.3f\n",sum);}
			else if(n==3) {printf("  1/1＋1/3＝%.3f\n",sum);}
			else if(n==5) {printf("  1/1＋1/3＋1/5＝%.3f\n",sum);}
			else if(n==7) {printf("  1/1＋1/3＋1/5＋1/7＝%.3f\n",sum);}
			else if(n==9) {printf("  1/1＋1/3＋1/5＋1/7＋1/9＝%.3f\n",sum);}
			else if(n==11){printf("  1/1＋1/3＋1/5＋1/7＋1/9＋1/11＝%.3f\n",sum);}
			else {printf("  1/1＋1/3＋1/5＋1/7＋1/9＋……＋1/%d＝%.3f\n",n,sum);}
		}

		printf("\n  是否继续求和吗？是则输入'y'或'Y'回车(或直接回车)，否则输入'n'或'N'回车 ");
		char flag;     
		if((flag=getchar())=='y'||flag=='Y'){;}
		else if((flag=getchar())=='n'||flag=='N'){break;}
			 else {while(getchar()!='\n'){;}}
	}
}