auto save

1.py

+data1=""
+file1=open(r'C:\Users\孙斌\Desktop\book.txt','r',encoding='utf-8')
+for data in file1:
+    if "小兰：12本" in data:
+        data=data.replace("小兰：12本","小兰：20本")
+    data1=data1+data
+print(data1)
+file1=open(r'C:\Users\孙斌\Desktop\book.txt','w',encoding='utf-8')
+file1.write(data1)
+file1.close()