"""
先给rw.txt文件写入 20行文字
再从rw.txt文件读取这20行文字
"""

with open('../res/rw.txt','a+',encoding='utf-8') as f :
    for line in range(20):
        f.write('这是第'+str(line)+'行\n')

with open('../res/rw.txt','r',encoding='utf-8') as f :
    for line in f:
        print(line,end="")
        
#　"with open('../res/rw.txt','r',encoding='utf-8') as f: " 的好处
# 可以让你变得更懒，它等于
f = open('../res/rw.txt','r',encoding='utf-8')
...
f.close()
# 可以省略掉f.close()，如果代码块短一点不会忘记关闭流文件，但是如果代码块大一点可能就容易忘记f.close()

with open('../res/rw.txt','r',encoding='utf-8') as f :
    print(f.read())

with open('../res/rw.txt','rb') as f :
    print(f.read())

with open('../res/rw.txt','r',encoding='utf-8') as f :
    print(f.read())

with open('../res/rw.txt','r',encoding='utf-8') as f :
    for line in f:
        print(line,end="")
        print("-"*5+"逐行输出"+"-"*5)

lis = []
for i in range(10):
    # 将字符串添加值lis列表末尾
    lis.append('这是第'+str(i)+'行\n')
with open('../res/rw.txt', 'a+', encoding='utf-8') as f:
    # 将整个列表写入到rw.txt文件
    f.writelines(lis)

lis = []
for i in range(10):
    lis.append('这是第'+str(i)+'行\n')
with open('../res/rw.txt', 'a+', encoding='utf-8') as f:
    # 遍历lis列表
    for line in range(len(lis)):
        # 将lis的每一个字符串写入rw.txt文件
        f.write(lis[line])

with open('../res/rw.txt','a+',encoding='utf-8') as f :
    for line in range(10):
        f.write('这是第'+str(line)+'行\n')
        print(f.readline())