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 prototypeint 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}