The for Loop

1. import std.stdio;
   
   void main() {
       for (int line = 0; line != 9; ++line) {
           for (int column = 0; column != 9; ++column) {
               write(line, ',', column, ' ');
           }
   
           writeln();
       }
   }
   

2. Triangle:

   import std.stdio;
   
   void main() {
       for (int line = 0; line != 5; ++line) {
           int length = line + 1;
   
           for (int i = 0; i != length; ++i) {
               write('*');
           }
   
           writeln();
       }
   }
   

   Parallellogram:

   import std.stdio;
   
   void main() {
       for (int line = 0; line != 5; ++line) {
           for (int i = 0; i != line; ++i) {
               write(' ');
           }
   
           writeln("********");
       }
   }
   

   Can you produce the diamond pattern?

      *
     ***
    *****
   *******
    *****
     ***
      *