warning: suggest parentheses around assignment used as truth value
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今天写代码:while((row = mysql_fetch_row(res)))
遇到gcc 编译器下居然发出了警告:warning:suggest parentheses around assignment used as truth value
找到了解决办法如下
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转自:http://blog.csdn.net/zhaoxiatengkong_1/article/details/6443824#
今天在写 词法分析器的时候 用了这么一句代码 :if (atype=search(alphatp,1))
结果在 gcc 编译器下居然发出了警告:warning:suggest parentheses around assignment used as truth value
郁闷!
后来在网络上找了一下 看人家是这么解释的,即在C语言中 非0代表TRUE ,反之为FALSE。 atype值是用于最后的判断用的,但是由于长期的编程实践告诉我们,人们经常在“=”和“==”的使用上出现手误,所以gcc编译器为此要求我们明确地告诉编译器它是“=”而不是“==”,是故意,而非手误。
if ((atype=search(alphatp,1))) 即加一个括号括起来就可以了。
既然我们的语句如上所示,并非要用“==”,因此我们只需修改成下列样式即可:
if ((atype=search(alphatp,1)))
- warning: suggest parentheses around assignment used as truth value
- warning: suggest parentheses around assignment used as truth value
- warning:suggest parentheses around assignment used as truth value
- warning: suggest parentheses around assignment used as truth value
- warning: suggest parentheses around assignment used as truth value
- warning: suggest parentheses around assignment used as truth value
- warning: suggest parentheses around assignment used as truth value
- warning: suggest parentheses around assignment used as truth value
- warning: suggest parentheses around assignment used as truth value
- warning: suggest parentheses around assignment used as truth value
- warning:suggest parentheses around assignment used as truth value
- warning: suggest parentheses around assignment used as truth value
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