auto save

diy.py

+with open(r"C:\Users\XMBC\Desktop\test.txt",'w',encoding="utf_8") as file1:
+    file1.write("小明:20本\n")
+    file1.write("小红:20本\n")
+    file1.write("小强:20本\n")
+    file1.write("小李:20本\n")
+with open(r"C:\Users\XMBC\Desktop\test.txt",'a',encoding="utf_8") as file1:
+    file1.write("小a:23本\n")
+    file1.write("小b:25本\n")
+    file1.write("小c:27本\n")
+with open(r"C:\Users\XMBC\Desktop\test.txt",'r',encoding="utf_8") as file1:
+    print(file1.read())
\ No newline at end of file

sales_list.txt

+小a
+小b
+小c
+小d
+小e
+小f
+小g
+小
+小
+小
+小
+小
+小
+小
+小
+小
+小
+小
+小
+小
+小
+小
+小
+小
+小
+小
\ No newline at end of file