程序代码：

#include <stdio.h>
#include <ctype.h>

int main(void)
{
    char answer = 'N';
    double total = 0.0;
    double value = 0.0;
    int count = 0;

    printf ("\nThis program calculates the average of any number of values.");

    for ( ; ; )
    {
        printf ("\nEnter a value: ");
        scanf ("%lf",&value);
        total += value;
        ++count;

        printf ("Do you want to enter another value ? (Y or N):");
        scanf ("%c",&answer);//这里本来要用户输入y 或者n确定是否继续循环，但是编译后无法输入y or n，编译一下就明白了。

        if (tolower (answer)== 'n')

        break;
    }
    printf ("\nThe average is %.2f\n",total/count);
    return 0;
}