運算符優先級決定的條款在表達式中的分組。這會影響一個表達式如何計算。某些運算符的優先級高於其他;例如，乘法運算符的優先級比加法運算符高。

例如X =7 +3* 2; 這裡，x被賦值13，而不是20，因為運算符*的優先級高於+，所以它首先被乘以3 * 2，然後再加上7。

這裡，具有最高優先級的操作出現在表的頂部，那些具有最低出現在底部。在表達式中，優先級較高的運算符將首先計算。

分類	Operator	關聯
Postfix	() [] -> . ++ - -	Left to right
Unary	+ - ! ~ ++ - - (type)* & sizeof	Right to left
Multiplicative	* / %	Left to right
Additive	+ -	Left to right
Shift	<< >>	Left to right
Relational	< <= > >=	Left to right
Equality	== !=	Left to right
Bitwise AND	&	Left to right
Bitwise XOR	^	Left to right
Bitwise OR	|	Left to right
Logical AND	&&	Left to right
Logical OR	||	Left to right
Conditional	?:	Right to left
Assignment	= += -= *= /= %=>>= <<= &= ^= |=	Right to left
Comma	,	Left to right

例子

試試下麵的例子就明白了在D編程語言中的運算符優先級可供選擇：

import std.stdio;

int main(string[] args)
{
   int a = 20;
   int b = 10;
   int c = 15;
   int d = 5;
   int e;
   e = (a + b) * c / d;      // ( 30 * 15 ) / 5
   writefln("Value of (a + b) * c / d is : %d
",  e );
   e = ((a + b) * c) / d;    // (30 * 15 ) / 5
   writefln("Value of ((a + b) * c) / d is  : %d
" ,  e );
   e = (a + b) * (c / d);   // (30) * (15/5)
   writefln("Value of (a + b) * (c / d) is  : %d
",  e );
   e = a + (b * c) / d;     //  20 + (150/5)
   writefln("Value of a + (b * c) / d is  : %d
" ,  e );
   return 0;
}

當編譯並執行上麵的程序它會產生以下結果：

Value of (a + b) * c / d is : 90
Value of ((a + b) * c) / d is  : 90
Value of (a + b) * (c / d) is  : 90
Value of a + (b * c) / d is  : 50