error LNK2019: 无法解析的外部符号 _main，该符号在函数 ___tmainCRTStartup 中被引用

Question

// power.c -- raises numbers to integer powers
#include <stdio.h>
double power(double n, int p); // ANSI prototype
int main(void)
{
    double x, xpow;
    int exp;

    printf("Enter a number and the positive integer power");
    printf(" to which\nthe number will be raised. Enter q");
    printf(" to quit.\n");
    while (scanf("%lf%d", &x, &exp) == 2)
    {
        xpow = power(x,exp);   // function call
        printf("%.3g to the power %d is %.5g\n", x, exp, xpow);
        printf("Enter next pair of numbers or q to quit.\n");
    }
    printf("Hope you enjoyed this power trip -- bye!\n");
 
    return 0;
}

double power(double n, int p)  // function definition
{
    double pow = 1;
    int i;

    for (i = 1; i <= p; i++)
        pow *= n;
        
    return pow;                // return the value of pow
}