C语言不关闭运行窗口循环

Question

运行完了不关闭可以继续运行，求教育
#include<stdio.h>
void main()
{
float x,rate;
printf("请输入购物金额:");
scanf("%f",&x);
if (x<300)
rate=1.0;

else if (x<=499)
rate=0.9;
else if (x<=800)
rate=0.7;
else
rate=0.5;
printf("x=%.2f,rate=%.2f,x*rate=%.2f\n",x,rate,x*rate);
}
该加在哪里

Answer 1

#include<stdio.h>
void main()
{
    float x,rate;
    char c;
    do
    {
        printf("请输入购物金额:");
        scanf("%f",&x);
        if (x<300)
            rate=1.0;
        else if (x<=499)
            rate=0.9;
        else if (x<=800)
            rate=0.7;
        else
            rate=0.5;
        printf("x=%.2f,rate=%.2f,x*rate=%.2f\n",x,rate,x*rate);
        printf("再次计算？Y:N\n");
        fflush(stdin);
        scanf("%c",&c);
    }while(c=='Y' || c=='y');
}

Answer 2

#include<stdio.h>
void main()
{
float x,rate;
char ch;
do
{
printf("请输入购物金额:");
scanf("%f",&x);
if (x<300)
rate=1.0;

else if (x<=499)
rate=0.9;
else if (x<=800)
rate=0.7;
else
rate=0.5;
printf("x=%.2f,rate=%.2f,x*rate=%.2f\n",x,rate,x*rate);
printf("是否继续(Y/N)?");
scanf("%c",&ch);
}while(ch=='Y'||ch=='y')

}

Answer 3

#include<stdio.h>
void main()
{
float x,rate;
while(1)
{
printf("\n请输入购物金额:");
scanf("%f",&x);
if (x<300)
rate=1.0;

else if (x<=499)
rate=0.9;
else if (x<=800)
rate=0.7;
else
rate=0.5;
printf("x=%.2f,rate=%.2f,x*rate=%.2f\n",x,rate,x*rate);
}
}