87 lines
1.7 KiB
Markdown
87 lines
1.7 KiB
Markdown
|
### 读文件
|
|||
|
|
|
|||
|
|
- 读取全部内容
|
|||
|
|
|
|||
|
|
```python
|
|||
|
|
f = open("xxx.py")
|
|||
|
|
f.read()
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
- 读取指定多少个字符内容
|
|||
|
|
|
|||
|
|
```python
|
|||
|
|
f = open("xxx.py")
|
|||
|
|
f.read(2)
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
- 按行读取：如果返回空就代表文件读完了
|
|||
|
|
|
|||
|
|
```python
|
|||
|
|
>>> f = open("xxx.py")
|
|||
|
|
>>> f.readline()
|
|||
|
|
'This is the first line of the file.\n'
|
|||
|
|
>>> f.readline()
|
|||
|
|
'Second line of the file\n'
|
|||
|
|
>>> f.readline()
|
|||
|
|
''
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
- 读取所有行到list
|
|||
|
|
|
|||
|
|
```python
|
|||
|
|
>>> f = open("module_support.py")
|
|||
|
|
>>> f.readlines()
|
|||
|
|
['#!/usr/bin/python3\n', '\n', 'def add(a, b):\n', ' return a + b\n', '\n', 'if __name__ == "__main__":\n', ' print("__main__")\n', 'else:\n', ' print(__name__)\n']
|
|||
|
|
>>>
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
- for循环读取每一行
|
|||
|
|
|
|||
|
|
```python
|
|||
|
|
>>> f = open("module_support.py")
|
|||
|
|
>>> for line in f:
|
|||
|
|
... print(line, end = "")
|
|||
|
|
...
|
|||
|
|
#!/usr/bin/python3
|
|||
|
|
|
|||
|
|
def add(a, b):
|
|||
|
|
return a + b
|
|||
|
|
|
|||
|
|
if __name__ == "__main__":
|
|||
|
|
print("__main__")
|
|||
|
|
else:
|
|||
|
|
print(__name__)
|
|||
|
|
>>>
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
### 写文件
|
|||
|
|
|
|||
|
|
```python
|
|||
|
|
f = open("module_support.py", "a") # 追加
|
|||
|
|
f = open("module_support.py", "w") # 文件不存在创建，存在就清空
|
|||
|
|
f.wtite("one line string")
|
|||
|
|
f.close()
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
### 文件操作cursor
|
|||
|
|
|
|||
|
|
- f.tell() 显示当前cursor位置
|
|||
|
|
- f.seek(offset, from_what) 重新设置cursor位置
|
|||
|
|
- from_what 的值, 如果是 0 表示开头, 如果是 1 表示当前位置, 2 表示文件的结尾，例如：
|
|||
|
|
- seek(x, 0) ： 从起始位置即文件首行首字符开始移动 x 个字符
|
|||
|
|
- seek(x, 1) ： 表示从当前位置往后移动x个字符
|
|||
|
|
- seek(-x, 2)：表示从文件的结尾往前移动x个字符
|
|||
|
|
|
|||
|
|
```python
|
|||
|
|
>>> f = open("module_support.py", "a")
|
|||
|
|
>>> f.tell()
|
|||
|
|
128
|
|||
|
|
>>> f = open("module_support.py", "a")
|
|||
|
|
>>> f.seek(10, 0)
|
|||
|
|
10
|
|||
|
|
>>>
|
|||
|
|
```
|
|||
|
|
|