|之间的差异和||或&和&&用于比较 [英] Difference between | and || or & and && for comparison

问题描述

可能重复：

与|和||或&和&&

  if（test = = test1 | test1 == test2）或if（test == test1 || test1 == test2）
 if（test == test1& test1 == test2）or if（test == test1& test1 == test2）
  

解决方案

可能）单个 | 或& 是按位比较。

double || 或&&& 是一种逻辑比较。

阅读Mehrdad关于无短路的评论

实际上，由于 true 通常等于 1 和 false 通常等价于 0 ，按位比较有时可能有效，并且返回完全相同的结果。

曾经有一个任务关键软件组件我运行了静态代码分析器，并指出，在进行逻辑比较时，使用逐位比较。由于它是用C语言编写的，并且由于逻辑比较的安排，软件与任何一个都很好地工作。示例：

  if（（altitide> 10000）&（knots> 100））
 ... 
  

Possible Duplicate:
A clear, layman’s explanation of the difference between | and || in c# ?

What is the difference between comparing with | and || or & and && in C# and Javascript?

Examples:

if(test == test1 | test1 == test2) or if(test == test1 || test1 == test2)
if(test == test1 & test1 == test2) or if(test == test1 && test1 == test2)

解决方案

in C (and other languages probably) a single | or & is a bitwise comparison.
The double || or && is a logical comparison.
Edit: Be sure to read Mehrdad's comment below regarding "without short-circuiting"

In practice, since true is often equivalent to 1 and false is often equivalent to 0, the bitwise comparisons can sometimes be valid and return exactly the same result.

There was once a mission critical software component I ran a static code analyzer on and it pointed out that a bitwise comparison was being used where a logical comparison should have been. Since it was written in C and due to the arrangement of logical comparisons, the software worked just fine with either. Example:

if ( (altitide > 10000) & (knots > 100) )
...

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