int counter=0;
for(int i=0;i<array.Length;i++){
  string lin="";
  for(int j=0;j<array[i].Length;j++){
    lin+=array[i][j]+" ";
  }
  lin=lin.Trim();
  writeline2file(lin);
  counter++
  if(counter%=5)
    writeline2file("A A A A A..");
}

------解决方案--------------------
探讨

一个二维数组，想输出到文档中，格式如下：

1  6   11  16  21  26
2  7   12  17  22  27          
3  8   13  18  23  28         
4  9   14  19  24  29       
5  10  15  20  25  30
A  A   A   A   A   A
31 36  41  46……


------解决方案--------------------
C# code
StringBuilder value = new StringBuilder();
            int length = 1000000;
            int rowlength = 5;
            int collength = 1 + rowlength;
            int ilength = (int)Math.Ceiling((double)(length / rowlength));
            int mod = length % collength;
            if (mod == 0)
            {
                mod = collength;
            }
            int mini = 0;
            for (int i = 1; i <= ilength; i++)
            {
                int jlength;
                if (i < ilength)
                {
                    jlength = collength;
                }
                else
                {
                    jlength = mod;
                }                
                for (int j = 0; j < jlength-1; j++)
                {
                    value.AppendFormat("{0} ",i+ mini + j * rowlength);
                }
                value.AppendFormat("{0}\r\n", i + mini + (jlength - 1) * rowlength);
                if (i % rowlength == 0)
                {
                    value.Append("A A A A A A\r\n");
                    mini += rowlength * rowlength;
                }
            }
            using (StreamWriter sw = new StreamWriter("./1.txt", false, System.Text.Encoding.UTF8, 8196))
            {
                sw.Write(value.ToString());               
            };
            MessageBox.Show("好了");