diy.py

# 写入同学们的捐赠明细：、'小丽：11本'、'李文：9本'、'张伟：16本'
filel=open(r'C:\Users\Administrator\Desktop\test.txt','w',encoding='utf-8')
filel.write('小丽:11本\n')
filel.write('李文:9本\n')
filel.write('张伟:16本\n')
filel.close()
with open(r'C:\Users\Administrator\Desktop\test.txt','a',encoding='utf-8')as file:
    file.write('小强:10本\n')
    file.write('李明:15本\n')
with open(r'C:\Users\Administrator\Desktop\test.txt','r',encoding='utf-8')as filel:
    for data in filel:
        if '小强:10本' in data:
            print('数据在文件中')
new_data=''
with open(r'C:\Users\Administrator\Desktop\test.txt','r',encoding='utf-8')as filel:
    for data in filel:
        if '小强:10本' in data:
            data=data.replace('小强:10本','小强:11本')
        new_data +=data
with open(r'C:\Users\Administrator\Desktop\test.txt','w',encoding='utf-8')as filel:
    filel.write(new_data)