(侵扰和搜查;真实的阴道、假和假装;假冒)经过“搜查”评估;“搜查”具有更高的优先地位。
TRUE && TRUE = True
FALSE && FALSE = False
True || False = True
Update:
1&&1||infiniteLoop()&&infiniteLoop()
为什么在C++中出现这种情况?
和以前一样,让我们打破分歧。 &&有更高的优先位置,即C++的短路短波和洋流。
1 && 1 = True.
当 b价值转换为 in升值时,
false -> 0
true -> 1
这一表述评价了这种(真实)和“和”的表述,即短路“The >,从而阻止了在限定时间内的休息。 正在编纂更多的陪审团,因此,对这种情况的简单看法就足够了。
NON-short 电路环境 这一表述永远不会被放弃,因为OR的双方都将“被评价”,右侧将hang。
如果你重新混淆了优先程度,那么,如果“......”、“......”、“......”、“......”、“......”、“......”、“......”、“......”?
1st.) True || False = True
2nd.) True && 1st = True
3rd.) 2nd && false = false
Expression = False;
我可以记住,如果它有权利离开或放弃权利,那么结果就是一样的。 在你的第二个岗位上,如果是< >高端:
1st.) 1||InfLoop(); Hang forever, but assuming it didn t
2nd.) 1 && 1st;
3rd.) 2nd && InfLoop(); Hang Forever
<>strong>tl;dr: 制作“灯”和“灯”;首先进行评价,但汇编者还短路播放OR。 实质上,汇编者将这种业务顺序归类(SIMLISTIC VIEW,第down<>>。 The pitchforks :-P
1st.) Is 1&&1 True?
2nd.) Evaluate if the Left side of the operation is true,
if so, skip the second test and return True,
Otherwise return the value of the second test(this is the OR)
3rd.) Is Inf() && Inf() True? (this would hang forever since
you have an infinite loop)
Update #2:
"However, this example proves && DOES NOT have precedence, as the || is evaluated before the second &&. This shows that && and || have equal precedence and are evaluated in left-to-right order."
“If && 优先评价第一个和计划;& (1),然后评价第二个和计划;& (有限住所)并保留方案。 由于这种情况没有发生,因此在进行“|”之前没有进行评估。
Let s cover these in detail.
在这里,我们再谈两个不同的问题。 确定业务秩序的预留和短档,这是为节省处理器周期而进行汇编/语文的切片。
Let s cover Precedence first. Precedence is short hand for "Order of Operations" In essence, given this statement:
1 + 2 * 3
in which order should the operations be grouped for evaluation?
数学明确规定,操作顺序比增加多。
1 + (2 * 3) = 1 + 2 * 3
2 * 3 is evaluated first, and then 1 is added to the result.
* has higher precedence than +, thus that operation is evaluated first.
现在,让人们转向风气表达方式:(&& = 和, Kluwer = OR)。
true AND false OR true
C++ 具有高于或高于其他标准的地位,
(true AND false) OR true
true AND false is evaluated first, and then
used as the left hand for the OR statement
因此,就在顺序上运行(真实和安插;真实的|、假和假装);
((true && true) || (false && false)) = (true && true || false && false)
1st Comparison.) true && true
2nd Comparison.) false && false
3rd Comparison.) Result of 1st comparison || Result of Second
With me thus far? Now lets get into Short Circuiting:
In C++, Boolean statements are what s called "short circuited". This means that the compiler will look at a given statement a choose the "best path" for evaluation. Take this example:
(true && true) || (false && false)
There is no need to evaluate the (false && false) if (true && true)
equals true, since only one side of the OR statement needs to be true.
Thus, the compiler will Short Circuit the expression. Here s the compiler s
Simplified logic:
1st.) Is (true && true) True?
2nd.) Evaluate if the Left side of the operation is true,
if so, skip the second test and return True,
Otherwise return the value of the second test(this is the OR)
3rd.) Is (false && false) True? Return this value
如你能看到,如果(真实和真实的)西非经货联盟得到评估,那么,如果(假装和假装)真的,就没有必要使用24小时周期评价。
C++ 短短环,但其他语文为所谓的“Eager”操作者提供机制。
例如,在Ada, “AND”和“OR”是“Eager”的操作者。
In Ada (true AND true) OR (false AND false) would evaluate both (true AND true) and (false AND false) before evaluating the OR. Ada Also gives you the ability to short circuit with AND THEN and OR ELSE, which will give you the same behavior C++ does.
我希望能充分回答你的问题。 否则,让我知道:-
<><>Update 3: 如果你再次提出问题,我就继续在电子邮件上分发。
“如果出现短路,就会发生,并且执行第二及厅的短路;以及说,这意味着“E”的操作员被处执行,第二和安放;操作员。 这意味着对“安放”和“安放”进行左对右执行;以及“安”和“安乐”;
接下来要看这个例子:
(false && infLoop()) || (true && true) = true (Put a breakpoint in InfLoop and it won t get hit)
false && infLoop() || true && true = true (Put a breakpoint in InfLoop and it won t get hit)
false || (false && true && infLoop()) || true = false (infLoop doesn t get hit)
If what you were saying was true, InfLoop would get hit in the first two.
You ll also notice InfLoop() doesn t get called in the third example either.
现在请看一下:
(false || true && infLoop() || true);
Infloop叫! 如果其他资源的预设率高于“备份”;“备份”,则汇编者将评估:
(false || true) && (infLoop() || true) = true;
(false || true) =true
(infLoop() || true = true (infLoop isn t called)
但是,InfLoop被叫! 这就是为什么:
(false || true && infLoop() || true);
1st Comparison.) true && InfLoop() (InfLoop gets called)
2nd Comparison.) False || 1st Comp (will never get here)
3rd Comparison.) 2nd Comp || true; (will never get here)
Precendece ONLY sets the grouping of operations. In this, && is greater than ||.
true && false || true && true gets grouped as
(true && false) || (true && true);
The Compiler Then出现并确定了它应当执行评价的顺序,以便它有最佳的储蓄周期。
Consider: false && infLoop() || true && true
Precedence Grouping goes like this:
(false && infLoop()) || (true && true)
The compiler then looks at it, and decides it will order the execution in this order:
(true && true) THEN || THEN (false && InfLoop())
这是一种事实,我不知道如何证明这一点。 优先程度由文法规则确定。 汇编者优化由每个汇编者确定,有些比其他汇编者更好,但All可自由调整分类的比较,因为它认为适当,以给其最快的“最佳”执行机会。
