描述

github上找到了一个Opencv3版本的代码，clone下来后编译提示错误

终端提示

use of undeclared identifier 'CV_EVENT_LBUTTONDOWN'; did you mean 'EVENT_LBUTTONDOWN'?

类似的提示还有

use of undeclared identifier 'CV_EVENT_LBUTTONUP'; did you mean 'EVENT_LBUTTONUP'?

use of undeclared identifier 'CV_BGR2HSV'; did you mean 'COLOR_BGR2HSV'?

use of undeclared identifier 'CV_HSV2BGR'; did you mean 'COLOR_HSV2BGR'?

use of undeclared identifier 'CV_MINMAX'

use of undeclared identifier 'CV_TERMCRIT_EPS'

use of undeclared identifier 'CV_TERMCRIT_ITER'

use of undeclared identifier 'CV_AA'

解决方案

• 原因：显而易见的是，Opencv版本不同时变量名称发生了改变，我的电脑是Opencv4

解决办法一

这种解决办法适合，Opencv4版本中仍然存在的变量

按照终端的提示，将错误的use of undeclared identifier变量名替换为did you mean后的变量名

• CV_EVENT_LBUTTONDOWN变为EVENT_LBUTTONDOWN
• CV_EVENT_LBUTTONUP变为EVENT_LBUTTONUP
• CV_BGR2HSV变为COLOR_BGR2HSV
• CV_HSV2BGR变为COLOR_HSV2BGR

解决办法

部分变量Opencv4已经删除了，这种时候就需要对未定义的变量进行声明

在代码中添加宏定义

#define CV_TERMCRIT_EPS 2
#define CV_TERMCRIT_ITER 1  
#define CV_AA 16

还有一个比较特殊的更改就是
将CV_MINMAX变量改成NORM_MINMAX，就可以解决