파일 입출력 - 이진(binary) 파일 읽기 쓰기

 

 

integer 10진수 11과 3을  이진파일에 쓰기

import struct  file = open('파일명.bin','wb+') tempbin = struct.pack('ii',11,3)##i는 int를 뜻하며 4바이트다. 다양한 포맷이 올수있다 i,h,c,I,B file.write(tempbin) file.close()

생성된 이진파일

0b 00 00 00 03 00 00 00

※ struct : python 자료형들을 'bytes' 형으로 변환 시켜준다.

struct.pack(fmt, v1, v2, ...)¶

Return a bytes object containing the values v1, v2, ... packed according to the format string fmt. The arguments must match the values required by the format exactly.

struct.pack_into(fmt, buffer, offset, v1, v2, ...)¶

Pack the values v1, v2, ... according to the format string fmt and write the packed bytes into the writable buffer buffer starting at position offset. Note that offset is a required argument.

struct.unpack(fmt, buffer)¶

Unpack from the buffer buffer (presumably packed by pack(fmt, ...)) according to the format string fmt. The result is a tuple even if it contains exactly one item. The buffer must contain exactly the amount of data required by the format (len(bytes) must equal calcsize(fmt)).

struct.unpack_from(fmt, buffer, offset=0)¶

Unpack from buffer starting at position offset, according to the format string fmt. The result is a tuple even if it contains exactly one item. buffer must contain at least the amount of data required by the format (len(buffer[offset:]) must be at least calcsize(fmt)).

struct.calcsize(fmt)¶

Return the size of the struct (and hence of the bytes object produced by pack(fmt, ...)) corresponding to the format string fmt.

Format(fmt)	C Type	Python type	Standard size	Notes
x	pad byte	no value
c	char	bytes of length 1	1
b	signed char	integer	1	(1),(3)
B	unsigned char	integer	1	(3)
?	_Bool	bool	1	(1)
h	short	integer	2	(3)
H	unsigned short	integer	2	(3)
i	int	integer	4	(3)
I	unsigned int	integer	4	(3)
l	long	integer	4	(3)
L	unsigned long	integer	4	(3)
q	long long	integer	8	(2), (3)
Q	unsigned long long	integer	8	(2), (3)
n	ssize_t	integer		(4)
N	size_t	integer		(4)
f	float	float	4	(5)
d	double	float	8	(5)
s	char[]	bytes
p	char[]	bytes
P	void *	integer		(6)

python 3.3 struct documentation : http://docs.python.org/py3k/library/struct.html

 

이진 파일 변형없이 읽어오기

try:     file = open('파일명.bin','rb')     while True:         temp = file.read(1)         if temp == '' : break         ## temp type 'bytes'         print("%02x "% ord(temp),end='')         ##ex) ord('a') -> 97 chr(97) -> 'a'     file.close() except IOError:     print("IO error")

결과

<원본 이진파일> d4 c3 00 02 18 f3 27 < print결과화면> d4 c3 00 02 18 f3 27

 

 

현재시간 timestamp 형 이진파일에 저장

import time import struct   file = open('파일명.bin','wb+') temptimestamp=time.time()##현재시간 timestamp 형으로 저장 tempchar = struct.pack('I',int(temptimestamp)) file.write(tempchar) file.close()

결과

10/06/2012 14:18:47 <이진 파일 내용> C7 3D 70 50