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'
#l=open(r'C:\Users\Administrator\Desktop\test.txt','w',encoding='utf-8')
#l.write('小兰:12本,小丽:11本\n')
#l.close()
new_data='' 
with open(r'C:\Users\Administrator\Desktop\test.txt','r',encoding='utf-8') as l:   
    for data in l:
        if '李文:9本' in data:
            data=data.replace('李文:9本','李文:10本')
        new_data+=data
with open(r'C:\Users\Administrator\Desktop\test.txt','w',encoding='utf-8') as l:   
  l.write(new_data)