error discription:
.cpp:187:25: warning: suggest parentheses around comparison in operand of ‘&’ [-Wparentheses] if (data_cur[j] == 255 & data_pre[j] == 255) temp.at<uchar>(i, j) = 255
why:
该警告希望你在&(逻辑与)表达式左右加上括号。有的时候&&(逻辑且)少写了一个&，也会产生该警告。
因为&运算符的优先级较低，低于==和！=运算符。
if ( (data_cur[j] == 255) && (data_pre[j] == 255) ) temp.at<uchar>(i, j) = 255;
RE
1.cnblogs-here;
End
suggest parentheses around comparison in operand of &|
原文：https://www.cnblogs.com/happyamyhope/p/9197230.html