C语言。求指教！请帮我写一下程序注释解释一下。已知公元1年1月1日是星期一。计算输入的年月日是星期几。

#include <stdio.h>
void main()
{
long year,month,day;
long totalday;
int week;
int monthday[12]={0,31,59,90,120,151,181,212,243,273,304,334};//什么意思？
int monthdayLeap[12]={0,31,60,91,121,152,182,213,244,274,305,335};//什么意思？
char * weekname[7]={"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"};//这个指针是什么意思？
printf("Please input Year Month Day:");
scanf("%ld %ld %ld",&year,&month,&day);
totalday=(year-1)*365+(year-1)/4-(year-1)/100+(year-1)/400;//这条语句是什么意思？
if((year%4==0)&&(year%100!=0)||(year%400==0))
totalday+=monthdayLeap[month-1];
else
totalday+=monthday[month-1];
totalday+=day;
week=totalday%7;//知道了week,怎么输出星期几？
printf("%ld,%s\n",totalday,weekname[week]);
}

int monthday[12]={0,31,59,90,120,151,181,212,243,273,304,334};//平常年份到该月1号之前共有多少天，1月1号之前0天 3月1号之前59天

int monthdayLeap[12]={0,31,60,91,121,152,182,213,244,274,305,335};//闰年到x月1号多少天
char * weekname[7]={"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"};//是指针的数组，不是指针，数组的每个成员是一个指针指向星期几的英语，用于最后的输出
printf("Please input Year Month Day:");
scanf("%ld %ld %ld",&year,&month,&day);
totalday=(year-1)*365+(year-1)/4-(year-1)/100+(year-1)/400;//计算迄今为止每年365天一共多少天加上闰年的个数（每个闰年增加天，被4整除是闰年 被100整除的不是 被400整除的是）
if((year%4==0)&&(year%100!=0)||(year%400==0))
totalday+=monthdayLeap[month-1];
else
totalday+=monthday[month-1];
totalday+=day;
week=totalday%7;//总共的天数对7求模得到余数
printf("%ld,%s\n",totalday,weekname[week]);
}

#include <stdio.h> void main() { long year,month,day; long totalday; int week; int monthday[12]={0,31,59,90,120,151,181,212,243,273,304,334};//monthday数组初始化 int monthdayLeap[12]={0,31,60,91,121,152,182,213,244,274,305,335};//monthdayLeap数组初始化 char * weekname[7]={"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"};//这是个指针数组，你也可以看成一个二维数组 printf("Please input Year Month Day:"); scanf("%ld %ld %ld",&year,&month,&day); totalday=(year-1)*365+(year-1)/4-(year-1)/100+(year-1)/400;//总天数 if((year%4==0)&&(year%100!=0)||(year%400==0)) totalday+=monthdayLeap[month-1]; else totalday+=monthday[month-1]; totalday+=day; week=totalday%7;//知道了week,怎么输出星期几？//下面那条语句就是输出星期几的 printf("%ld,%s\n",totalday,weekname[week]);//这个就是输出星期几的地方 }

#include <stdio.h> #include <windows.h> int main() { char szbuffer[512]; // 这个不用解释 dword nsize = sizeof( szbuffer ); // 这个sizeof是求出szbuffer大小，下面的这个函数需要用到它 getcomputername( szbuffer, &nsize );// 这个是获取计算机名的一个api，用法下面给你解释 printf( "本机的计算机名是: %s\n", szbuffer ); // 这个也不用解释了 }

getcomputername 的原型是

bool getcomputername( lptstr lpbuffer, lpdword lpnsize );

参数用法：

lpbuffer

[out] pointer to a buffer that receives a null-terminated string

输出用的，获取到计算机名后给你存放到这个参数中

lpnsize

[in, out] on input, specifies the size of the buffer

这个参数告诉getcomputername函数lpbuffer 能存储多少字符，函数调用完之后这个参数的值是得到的计算机名的长度。 if the buffer is too small, the function fails

如果你的字符数组空间太小函数就会执行失败，并且lasterror码就被置为error_buffer_overflow