Console.Write("请输入一个数字：");
try
{
int a = Convert.ToInt32(Console.ReadLine());
if (a % 2 != 0)
{
for (int i = 1; i <= (a+1)/2; i++)//菱形上半部分
{
int c = ((i * 2 - 1) + 1) / 2 - 1;//中间值
string end = "";
char b=‘a‘;
int count = 0;
bool d = false;
for (int j = 1; j <=(a+1)/2-i; j++)
{
end += " ";
}
for (int j = 1; j <= i * 2 - 1; j++)
{
end += b;
if (count == c)
{
d = true;
}
if (d)
{
if (b == ‘A‘)
{
b = ‘Z‘;
}
else
{
b--;
}
}
else
{
if (b == ‘Z‘)
{
b = ‘A‘;
}
else
{
b++;
}
count++;
}
}
Console.WriteLine(end);
}
for (int i = 1; i < (a + 1) / 2; i++)//菱形的下半部分
{
char b = ‘a‘;
int c = ((a - i * 2)+1) / 2 - 1;
string end = "";
int count = 0;
bool d = false;
for (int j = 1; j <= i; j++)
{
end += " ";
}
for (int j = 1; j < (a - i * 2) + 1; j++)
{
end += b;
if (count == c)
{
d = true;
}
if (d)
{
if (b == ‘A‘)
{
b = ‘Z‘;
}
else
{
b--;
}
}
else
{
if (b == ‘Z‘)
{
b = ‘A‘;
}
else
{
b++;
}
count++;
}
}
Console.WriteLine(end);
}
}
else
{
Console.Write("输入错误");
}
}
catch
{
Console.Write("输入错误");
}
Console.ReadLine();
//用户输入一个字母，如D，那么就打印 ABCDCBA
Console.Write("请输入一个字母");
char a = Convert.ToChar(Console.ReadLine());
char b = ‘a‘;
bool c = true;//判断b++或是b--
//拼接要打印的内容
for (int i = 1; i <= 26; i++)
{
Console.Write(b);
if (b == a)
{
c= false;
}
if (c)
{
b++;
}
else
{
b--;
if (b == ‘a‘ || b == ‘A‘)
{
Console.Write(b);
break;
}
}
}
Console.ReadLine();
原文：http://www.cnblogs.com/zoubizhici/p/5554861.html