#include<stdio.h>
#include<windows.h>
int main()
{
    float principal,rate,interest;
    int days;
    printf("enter loan principal (-1 to end):");
    scanf("%f",&principal);
    while(principal!=-1)
    {printf("enter interest rate:");
     scanf("%f",&rate);
     printf("enter term of the loan in days:");
     scanf("%f",&days);
     interest=(float)principal*rate*days/365;
     printf("the interest charge is:$%.2f\n",interest);
     printf("enter loan principal (-1 to end):");
     scanf("%f",&principal);}
     system("pause");
     return 0;}
不管输入什么数怎么输出都是31124214.00呀