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'
with open(r"C:\Users\windoins\Desktop\捐赠.txt","w",encoding="utf-8") as f:
    f.write("小兰:12本\n")
    f.write('小丽：11本\n')
    f.write('李文：9本\n')
    f.write("张伟：16本\n")
    f.write("小强：10本\n")
with open(r"C:\Users\windoins\Desktop\捐赠.txt","r",encoding="utf-8") as f:
    a=f.readlines()
    new_data=" "
    for data in a:
        
        if "小强：10本" in  data:
            print("数据在文件中")
            data=data.replace("小强：10本","小强：11本")
        new_data = new_data + data
    print(new_data)

with open(r"C:\Users\windoins\Desktop\捐赠1.txt","w",encoding="utf-8") as f:
    f.write(new_data)