语句：顺序，条件，循环
If ()//关系表达式
{}//语句
if(){}else{}//if(){}//if(){}else if(){}else{}
Console.WriteLine("年份：");
int Y = int.Parse(Console .ReadLine ());
Console.WriteLine("月份：");
int M = int.Parse(Console.ReadLine());
Console.WriteLine("日期 ：");
int D = int.Parse(Console.ReadLine());
if ((!(Y >= 1759 && Y <= 9999)) || ((M == 1 || M == 3 || M == 5 || M == 7 || M == 8 || M == 10 || M == 12) && (!(D > 0 && D <= 31))) || (!(M > 0 && M <= 12)) || (M == 4 || M == 6 || M == 9 || M == 11) && (!(D > 0 && D <= 30)))
{ Console.WriteLine("输入日期错误"); }
if ((Y % 400 == 0 || (Y % 100 != 0 && Y % 4 == 0) && M == 2 && (!(D > 0 && D <= 29))) || (M == 2 && (!(D > 0 && D <= 28))))
{ Console.WriteLine("输入日期错误"); }
else
{
int t = 0;
if (Y % 400 == 0 || (Y % 100 != 0 && Y % 4 == 0))
{
if (M == 1) { t += D; }
if (M == 2) { t += 31 + D; }
if (M == 3) { t += 31 + 29 + D; }
if (M == 4) { t += 31 + 29 + 31 + D; }
if (M == 5) { t += 30 + 29 + 31 + 30 + D; }
if (M == 6) { t += 30 + 29 + 31 + 30 + 31 + D; }
if (M == 7) { t += 30 + 29 + 31 + 30 + 31 + 30 + D; }
if (M == 8) { t += 30 + 29 + 31 + 30 + 31 + 30 + 31 + D; }
if (M == 9) { t += 30 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + D; }
if (M == 10) { t += 30 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + D; }
if (M == 11) { t += 30 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + D; }
if (M == 12) { t += 30 + 29 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30 + D; }
}
else
{
if (M == 1) { t += D; }
if (M == 2) { t += 31 + D; }
if (M == 3) { t += 31 + 28 + D; }
if (M == 4) { t += 31 + 28 + 31 + D; }
if (M == 5) { t += 30 + 28 + 31 + 30 + D; }
if (M == 6) { t += 30 + 28 + 31 + 30 + 31 + D; }
if (M == 7) { t += 30 + 28 + 31 + 30 + 31 + 30 + D; }
if (M == 8) { t += 30 + 28 + 31 + 30 + 31 + 30 + 31 + D; }
if (M == 9) { t += 30 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + D; }
if (M == 10) { t += 30 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + D; }
if (M == 11) { t += 30 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + D; }
if (M == 12) { t += 30 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30 + D; }
}
Console.WriteLine("这是第" + t + "天");*/
/* Console.WriteLine("输入一元二次方程：ax*x+bx+c=0");
Console.Write("a=");
double a = double.Parse(Console.ReadLine());
Console.Write("b=");
double b = double.Parse(Console.ReadLine());
Console.Write("c=");
double c = double.Parse(Console.ReadLine());
double e = b * b - 4 * a * c;
if (a == 0)
{ Console.WriteLine("这不是一个一元二次方程"); }
else
{
Console.WriteLine("这是一个一元二次方程");
if (e > 0)
{
double x1 = -b + Math.Sqrt(e) / (2 * a);
double x2 = -b - Math.Sqrt(e) / (2 * a);
Console.WriteLine("有两个不同的实根");
Console.WriteLine("两个根分别是：x1=" + x1.ToString() + " x2=" + x2.ToString());
}
else if (e == 0)
{
Console.WriteLine("有两个相同的实根");
double x1 = -b + Math.Sqrt(e) / (2 * a);
double x2 = -b - Math.Sqrt(e) / (2 * a);
Console.WriteLine("两个根分别是：x1=x2=" + x1.ToString());
}
else
{ Console.WriteLine("没有实根"); }*/
/* Console.WriteLine("0-石头，1-剪刀，2-布");
随机数 Random r =new Random();
Int shu =r.Next();
Console.Write("b ");
int b = int.Parse(Console.ReadLine());
Random r = new Random();
int a = r.Next(3);
int c = 0;
int d = 0;
if (b <= 2 && b >= 0)
{
if (a == 0) { Console.WriteLine("电脑出石头"); }
else if (a == 1) { Console.WriteLine("电脑出剪刀"); }
else { Console.WriteLine("电脑出布 "); }
if (a == b) { Console.WriteLine("平局"); }
else if ((b == 0 && a == 1) || (b == 2 && a == 0) || (b == 1 && a == 2)) { Console.WriteLine("你赢了"); c++; }
else if ((b == 0 && a == 2) || (b == 1 && a == 0) || (b == 2 && a == 1)) { Console.WriteLine("你输了"); d++; }
}
else { Console.WriteLine("输入错误 "); }*/
/* int a = 0;
for (int i = 1; i <= 100; i++)
{
a += i;
}
Console.WriteLine(a);
*/
/* Console.WriteLine("输入数字：");
int n = int.Parse(Console .ReadLine ());
for (int i = 1; i <=n; i++)
{
Console.WriteLine(i);
}*/
/*int a = 0;
for (int i = 0; i <=100; i=i +2)
{
a += i;
}
Console.WriteLine(a);*/
/* Console.WriteLine("0-石头，1-剪刀，2-布");
Random r = new Random();
int a = r.Next(3);
int H = 0;
int C = 0;
if (a == 0) { Console.WriteLine("电脑出石头"); }
else if (a == 1) { Console.WriteLine("电脑出剪刀"); }
else { Console.WriteLine("电脑出布 "); }
for (int i =1; i <= 3; i++)
{
Console.Write("b ");
int b = int.Parse(Console.ReadLine());
if (b == 0)
{
if (a == 0) { Console.WriteLine("平局"); }
if (a == 1) { Console.WriteLine("你赢了"); H++; }
if (a == 2) { Console.WriteLine("电脑赢了"); C++; }
}
else if (b==1)
{
if (a == 0) { Console.WriteLine("电脑赢了"); C++; }
if (a == 1) { Console.WriteLine("平局"); }
if (a == 2) { Console.WriteLine("你赢了"); H++; }
}
else if (b == 2)
{
if (a == 0) { Console.WriteLine("你赢了"); H++; }
if (a == 1) { Console.WriteLine("电脑赢了"); C++; }
if (a == 2) { Console.WriteLine("平局"); }
}}
if(H>C){Console.WriteLine("你赢了");}
else if (C > H) { Console.WriteLine("电脑赢了"); }
else { Console.WriteLine("平局"); }*/
/* int a = 0;
for (int i = 1; i <= 100; i ++)
{
if (i % 2 == 0)
{ a += i; }
}
Console.WriteLine(a);*/