在C语言中指定IF条件内的范围
我只想知道这些C代码段之间的区别。我以两种不同的方式使用了它，最终输出不相同。
if(120<=units<160){
total= total- total*(15.0/100);
printf("Revenue : %.2f", total);
}
if(120<=units && units<160){
total= total- total*(15.0/100);
printf("Revenue : %.2f", total);
}
我们不能使用“ 120＆lt; =单位＆lt; 160”来指定C语言的范围？
I just want to know the difference between these C code segments. I used it in two different ways and final output was not same.
if(120<=units<160){
total= total- total*(15.0/100);
printf("Revenue : %.2f", total);
}
if(120<=units && units<160){
total= total- total*(15.0/100);
printf("Revenue : %.2f", total);
}
Can't we use "120<=units<160" to specify a range in C language?
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不，您不能以这种方式测试范围。这里发生的事情是按照操作员优先。
因此，这意味着：
（120＆lt; =单位）＆lt; 160120＆lt; =单位的值如果为false或 1如果换句话说，完整的表达将始终是正确的，因为0和1均小于160。
No, you can't test ranges in this way. What's happening here is the operators are evaluated left-to-right as per operator precedence.
So this means:
(120 <= units) < 160The value of
120 <= unitswill be 0 if it is false or 1 if it is trueIn other words, the full expression will always be true, because both 0 and 1 are less than 160.
它被解析为这两个（我不记得哪一个）之一：
（120＆lt; = units）＆lt; 160120＆lt; =（单位＆lt; 160）在这两种情况下，都进行了一个比较，产生一个“ boolean”（
0或1）与其他数字进行比较，通常会导致“错误”结果（嗯，这是完全正确的，只是不符合您的期望）It's parsed as one of these two (I don't remember which):
(120 <= units) < 160120 <= (units < 160)In both cases, one comparison is done, yielding a "boolean" (
0or1) which is then compared with the other number, typically leading to a "wrong" result (well, it's perfectly correct, just doesn't match your expectation)这个问题类似于C ++的帖子。您可以参考下面链接中的帖子。 https://stackoverflow.com/a/3831148/19395482
The question is similar to a post in C++. You can refer to the post in the link below. https://stackoverflow.com/a/3831148/19395482
By Matthieu M.: