Python入门示例系列24 文件读写
文件操作的模式
文件操作的模式如下表:
1. open 打开文件
使用 open 打开文件后一定要记得调用文件对象的 close() 方法。比如可以用 try/finally 语句来确保最后能关闭文件。
file_object = open(r'D:\test.txt')
try:
all_the_text = file_object.read( )
finally:
file_object.close( )
print(all_the_text)
注:不能把 open 语句放在 try 块里,因为当打开文件出现异常时,文件对象 file_object 无法执行 close() 方法。
2. 读文件
读文本文件方式打开文件
file_object = open(r'D:\test.txt', 'r')
#第二个参数默认为 r
file_object = open(r'D:\test.txt')
读二进制文件方式打开文件
file_object= open(r'D:\test.txt', 'rb')
读取所有内容
file_object = open(r'D:\test.txt')
try:
all_the_text = file_object.read( )
finally:
file_object.close( )
print(all_the_text)
读固定字节
file_object = open(r'D:\test.txt', 'rb')
try:
while True:
chunk = file_object.read(100)
if not chunk:
break
#do_something_with(chunk)
finally:
file_object.close( )
读每行 readlines
file_object = open(r'D:\test.txt', 'r')
list_of_all_the_lines = file_object.readlines( )
print(list_of_all_the_lines)
file_object.close( )
如果文件是文本文件,还可以直接遍历文件对象获取每行:
file_object = open(r'D:\test.txt', 'r')
for line in file_object:
print(line)
file_object.close( )
3. 写文件
写文本文件方式打开文件
file_object= open('data', 'w')
写二进制文件方式打开文件
file_object= open('data', 'wb')
追加写文件方式打开文件
file_object= open('data', 'w+')
写数据
all_the_text="aaa\nbbb\nccc\n"
file_object = open(r'D:\thefile.txt', 'w')
file_object.write(all_the_text)
file_object.close( )
写入多行
all_the_text="aaa\nbbb\nccc\n"
file_object = open(r'D:\thefile.txt', 'w')
file_object.writelines(all_the_text)
file_object.close( )
追加
file = r'D:\thefile.txt'
with open(file, 'a+') as f:
f.write('aaaaaaaaaa\n')
REF
https://www.cnblogs.com/emanlee/p/4033526.html
https://www.cnblogs.com/emanlee/p/3871723.html
https://www.runoob.com/python3/python3-file-methods.html