这是一位高级经理在面试时问的问题。
哪个更快?
while(1) {
// Some code
}
or
while(2) {
//Some code
}
我说过两者具有相同的执行速度,因为while中的表达式最终应求值为true或false。在这种情况下,两者都求值为true,并且while条件中没有额外的条件指令。因此,两者将具有相同的执行速度,我更喜欢while(1)。
但面试官自信地说:
“检查你的基本知识。While(1)比While(2)快。”
(他不是在试探我的信心)
这是真的吗?
请参见:“for(;;)”是否比“while (TRUE)”快?如果不是,人们为什么要使用它?
我认为线索可以从“高级经理的询问”中找到。这个人显然在成为经理后就停止了编程,然后他/她花了几年时间才成为高级经理。从未失去对编程的兴趣,但从那以后再也没有写过一行字。所以他提到的并不是“任何一个像样的编译器”,而是“这个人在二三十年前合作过的编译器”。
At that time, programmers spent a considerable percentage of their time trying out various methods for making their code faster and more efficient as CPU time of 'the central minicomputer' was so valueable. As did people writing compilers. I'm guessing that the one-and-only compiler his company made available at that time optimized on the basis of 'frequently encountered statements that can be optimized' and took a bit of a shortcut when encountering a while(1) and evaluated everything else, including a while(2). Having had such an experience could explain his position and his confidence in it.
让你被录用的最好方法可能是,在你顺利地引导他进入下一个面试主题之前,让高级经理忘乎所以地给你讲2-3分钟“编程的美好时光”。(好的时机在这里很重要——太快你会打断故事——太慢你会被贴上焦点不集中的标签)。一定要在面试结束时告诉他,你对这个话题非常感兴趣。