原因: vs code 没有链接好 opencv 的头文件
先找到opencv头文件的位置: sudo find / -iname "opencv"
/usr/include/opencv4
/usr/include/opencv4/opencv2
解决: ctril + sheft + p :打开: c_cpp_properties.json ,写入:
"includePath": [
"${workspaceFolder}/**",
"/usr/include/opencv4",
"/usr/include/opencv4/opencv2"
],
即可解决!