下表列出了所有D语言支持的关系运算符。假设变量A=10和变量B=20，则：

运算符	描述	示例
==	检查，如果两个操作数的值相等与否，如果是则条件为真。	(A == B) is not true.
!=	检查，如果两个操作数的值相等与否，如果值不相等，则条件变为真。	(A != B) is true.
>	如果左操作数的值大于右操作数的值，如果是则条件为真检查。	(A > B) is not true.
<	如果检查左操作数的值小于右操作数的值，如果是则条件为真。	(A < B) is true.
>=	如果左操作数的值大于或等于右操作数的值，如果是则条件为真检查。	(A >= B) is not true.
<=	如果检查左操作数的值小于或等于右操作数的值，如果是则条件为真。	(A <= B) is true.

示例

试试下面的例子就明白了所有的D编程语言的关系运算符：

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
" );
   }
   else
   {
      writefln("Line 1 - a is not equal to b
" );
   }
   if ( a < b )
   {
      writefln("Line 2 - a is less than b
" );
   }
   else
   {
      writefln("Line 2 - a is not less than b
" );
   }
   if ( a > b )
   {
      printf("Line 3 - a is greater than b
" );
   }
   else
   {
      writefln("Line 3 - a is not greater than b
" );
   }
   /* Lets change value of a and b */
   a = 5;
   b = 20;
   if ( a <= b )
   {
      printf("Line 4 - a is either less than or equal to  b
" );
   }
   if ( b >= a )
   {
      writefln("Line 5 - b is either greater than  or equal to b
" );
   }
   return 0;
}

当编译并执行上面的程序它会产生以下结果：

Line 1 - a is not equal to b

Line 2 - a is not less than b

Line 3 - a is greater than b

Line 4 - a is either less than or equal to  b

Line 5 - b is either greater than  or equal to b

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