D語言關係運算符

下表列出了所有D語言支持的關係運算符。假設變量A=10和變量B=20，則：

運算符

描述

示例

==

檢查，如果兩個操作數的值相等與否，如果是則條件爲真。

(A == B) is not true.

!=

檢查，如果兩個操作數的值相等與否，如果值不相等，則條件變爲真。

(A != B) is true.

>

如果左操作數的值大於右操作數的值，如果是則條件爲真檢查。

(A > B) is not true.

<

如果檢查左操作數的值小於右操作數的值，如果是則條件爲真。

(A < B) is true.

>=

如果左操作數的值大於或等於右操作數的值，如果是則條件爲真檢查。

(A >= B) is not true.

<=

如果檢查左操作數的值小於或等於右操作數的值，如果是則條件爲真。

(A <= B) is true.

示例

試試下面的例子就明白了所有的D編程語言的關係運算符：

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; }

當編譯並執行上面的程序它會產生以下結果：

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