D语言关系运算符

import std.stdio;

int main(string[] args) { 
   int a = 21; 
   int b = 10; 
   int c ;  

   if( a == b ) { 
      writefln(Line 1 - a is equal to b\n ); 
   } else { 
      writefln(Line 1 - a is not equal to b\n );
   } 

   if ( a < b ) { 
      writefln(Line 2 - a is less than b\n ); 
   } else { 
      writefln(Line 2 - a is not less than b\n ); 
   } 

   if ( a > b ) { 
      writefln(Line 3 - a is greater than b\n ); 
   } else { 
      writefln(Line 3 - a is not greater than b\n ); 
   } 

   /* Lets change value of a and b */ 
   a = 5; 
   b = 20; 

   if ( a <= b ) { 
      writefln(Line 4 - a is either less than or equal to b\n ); 
   } 
   if ( b >= a ) { 
      writefln(Line 5 - b is either greater than or equal to b\n ); 
   } 
   return 0; 
}