import os
import string
#找到指定文件夹
dirName = "C:/Users/User/Desktop/labelme/data/"
li=os.listdir(dirName)
for filename in li:
newname = filename
filename = dirName+filename
newname = newname.split(".")
#改名字"****.jpg"__--->"****.png",再覆盖原来的名字
if newname[-1]=="jpg":
newname[-1]="png"
newname = str.join(".",newname) #这里要用str.join
newname = dirName+newname
os.rename(filename,newname)
print(newname,"updated successfully")