C语言中"for"循环中的两个变量 [英] Two variables in a 'for' loop in C

问题描述

我正在编写一些代码，需要在for循环中使用两个变量.下面的代码看起来还不错吗?

I am writing some code where I need to use two variables in a for loop. Does the below code seem alright?

它确实给了我预期的结果.

It does give me the expected result.

for (loop_1 = offset,loop_2 = (offset + 2); loop_1 >= (offset - 190),loop_2 <= (190 + offset + 2); loop_1--,loop_2++)
{
    if (  (*(uint8_t*)(in_payload + loop_1) == get_a1_byte(bitslip)) &&
         ((*(uint8_t*)(in_payload + loop_2) == get_a2_byte(bitslip)))
       )
    {
          a1_count++;
    }
}

但是我收到一个编译器警告，内容为:

But I am getting a compiler warning which says:

file.c:499:73:警告:逗号表达式的左侧操作数无效

file.c:499:73: warning: left-hand operand of comma expression has no effect

这是什么意思?

推荐答案

问题是测试条件:

loop_1 >= (offset - 190),loop_2 <= (190 + offset + 2)

这不会同时检查两个部分. (当然，但是只使用第二部分的结果.)

This does not check both parts. (Well, it does, but only the result of the second part is used.)

将其更改为

(loop_1 >= (offset - 190)) && (loop_2 <= (190 + offset + 2))

如果要同时检查两个条件.

if you want both conditions to be checked.

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