Python read write file binary

Do I need to use struct? Here is an attempt with the original function, in this case is the result which is incorrect:. What it does is pad the length of the data up to a whole multiple of 4 bytes, xor's that with the four-byte key, but then only writes out data that was the length of the original.

This problem was a little tricky because the byte-order of the data for a 4-byte key depends on your processor but is always written with the high-byte first, but the byte order of string or bytearrays is always written low-byte first as shown in your hex dumps. To allow the key to be specified as a hex integer, it was necessary to add code to conditionally compensate for the differing representations -- i.

I'm not sure you're actually taking the input by 4 bytes, but I didn't try to decipher it. This assumes your input is divisible by 4. How are we doing? Please help us improve Stack Overflow. Take our short survey. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Read and write binary file in Python Ask Question.

Asked 9 years, 6 months ago. Active 9 years, 6 months ago. Viewed 32k times. In Python, the IO module provides methods of three types of IO operations; raw binary files, buffered binary files, and text files. The canonical way to create a file object is by using the open function. If you specify the char size argument in the read chars method, then it will read that many chars only. As you can see, we have to open the file in 'r' mode. The readline method will return the first line, and then will point to the second line in the file.

The file object has an inbuilt iterator. The following program reads the given file line by line until StopIteration is raised, i. Next, f. It returns the number of characters written to a file, which is 5 in the above example. In the end, f. Python provides the writelines method to save the contents of a list object in a file. Python read a binary file into a byte array. Python read a binary file line by line. Python read a binary file to Ascii.

Python read a binary file into a NumPy array. Python read a binary file into CSV. Bijay Kumar. Read the entire file as a single byte string.

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