简单的逻辑问题：检查x是否在2个数字之间 [英] simple logic question: check if x is between 2 numbers

问题描述

我想查看变量是否介于一定范围的值之间，例如，如果x在20到30之间，则返回true。

I want to see if a variable is between a range of values, for example if x is between 20 and 30 return true.

最快的方法是这（用任何C语言）？

What's the quickest way to do this (with any C based language)?

显然可以使用for循环：

It can obviously be done with a for loop:

function inRange(x, lowerbound, upperbound)
{
  for(i = lowerbound; i < upperbound; i++)
  {
    if(x == i) return TRUE;
    else return FALSE;
  }
}
//in the program
if(inRange(x, 20, 30))
   //do stuff

但如果（inRange（x，20，30））

but it's awful tedious to do if(inRange(x, 20, 30)) is there simpler logic than this that doesn't use built in functions?

推荐答案

你想要的表达式是

20 <= x && x <= 30

编辑：

或者只是放入函数

function inRange(x, lowerbound, upperbound)
{
  return lowerbound <= x && x <= upperbound;
}

Python在 in 运算符：

Python has an in operator:

>>> r = range(20, 31)
>>> 19 in r
False
>>> 20 in r
True
>>> 30 in r
True
>>> 31 in r
False

同样在Python中，链接！这完全不同于C和Java。请参见 http://en.wikipedia.org/wiki/Python_syntax_and_semantics#Comparison_operators

Also in Python, and this is pretty cool -- comparison operators are chained! This is totally unlike C and Java. See http://en.wikipedia.org/wiki/Python_syntax_and_semantics#Comparison_operators

所以你可以写

low <= x <= high

在Python -10 <= -5 <= -1 是True，但在C中它是false。尝试一下。 ：）

In Python -10 <= -5 <= -1 is True, but in C it would be false. Try it. :)

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