Read integer from binary file in Python

Question

I have the following snippet of C code:

#include <stdio.h>
void main(){
  int a = 1308901095;
  FILE *fp;
  fp = fopen("file", "wb");
  fwrite(&a, sizeof(int), 1, fp);
  fclose(fp);
  printf("Done\n");
}

This will write the "a" integer in file "file", in binary form.

How I can read this number in Python?

Small tip: If you're transferring this binary file between computers, be sure to consider endianness and the size of your int. — csl
– csl, Commented Jun 24, 2011 at 9:05

mattn · Accepted Answer · 2011-06-24 08:51:39Z

3

Try following.

from struct import *
f = open('file', 'rb')
print unpack('<i', f.read(4))[0]
f.close()

note that using '<' about your machine is little endian or not.

answered Jun 24, 2011 at 8:51

mattn

7,77333 silver badges54 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Léo Germond Over a year ago

You should replace '>' or '<' by '@' to use native endianess. Source: docs.python.org/library/…

johnsyweb Over a year ago

@Leo: Presuming the file is being read by the same machine (architecture) as the one that did the writing.

Léo Germond Over a year ago

@john, Yes tou are totally right about that, I was just "completing" your answer.

Collectives™ on Stack Overflow

Read integer from binary file in Python

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related