文件操作

f = open('user.txt','r')  #文件句柄
f1 = open('user.txt','w')  #覆盖写入
f2 = open('user.txt','a')  #追加到文件内容到末尾

with open('user.txt','r') as f:  #自动关闭文件
    pass

#读写模式

f = open('user.txt','r+')  #读写
print(f.readline().strip())
print(f.readline().strip())
print(f.readline().strip())
f.write("
------------")
f.tell()             #获取当前文件读取指针的位置
f.seek(0)            #用于移动文件读写指针到指定的位置

#修改文件

f = open('user.txt','r')#读写
f_2 = open('simple.txt','w')

for i in f:
     if 'xxxxxxx' in i:
         i = i.replace("xxxxxxx","55444")
     f_2.write(i)
f.close()
f_2.close()

#修改文件2

with open('user.txt','r') as f,
     open('simple.txt','w') as f_2:
    for i in f:
         if 'xxxxxxx' in i:
             i = i.replace("xxxxxxx","111111111")
         f_2.write(i)

#打印几行

for i in  range(1,5):
    print(f.readline().strip())

#跳过第二行,如果文件过大readlines会占用大量内存

for index,line in enumerate(f.readlines()):
    if index == 2:
        continue
    print(index, line.strip())

#高效的循环

count = 0
for line in f:
    count += 1
    if count == 2:
        print("-----替代-----")
        continue
    print(line.strip())