auto save

diy.py

+# 写入同学们的捐赠明细：'小兰：12本'、'小丽：11本'、'李文：9本'、'张伟：16本'
+newdata = ''
+f=open('./test.txt','w',encoding='UTF-8')
+f.write("小兰:12本\n")
+f=open('./test.txt','a',encoding='UTF-8')
+f.write("小丽:11本\n")
+f.write("李文:9本\n")
+f.write("张伟:16本\n")
+f.close()
+
+with open('./test.txt','r',encoding='UTF-8') as f:
+    for data in f:
+        if'小兰' in data:
+            print("小兰在数据中")
+            data.replace('小兰:12','小兰:17')
+        newdata+=data
+
+with open('./test.txt','w',encoding='UTF-8') as f:
+    f.write(newdata)
\ No newline at end of file

test.txt

+小兰:12本
+小丽:11本
+李文:9本
+张伟:16本