python-opencv的cv2.imwriter()命令如何用变量名来保存图片

cv2.imwrite("./change__0/" + file[i] , pre1__picture) _ #图片保存名应为变量

加个str，试试
"./change__0/" +str（file[i]）

cv2.imwrite("./change__0/" +str( file[i]) , pre1__picture)

sprintf_s(s, "%04d", 变量);
filename = "E:\negative\" + (string)s + ".png";
imwrite(filename, Mat变量);