用Python写入txt文件

Question

I'm having issues printing to a txt file. The file contains information stored in bytes. No matter what I try, I can only get the output to print in the shell. Here's what I have - any help is welcome.

def main():
    with open("in.txt", "rb") as f:
        byte = f.read(1)
        while byte != "":
            print ord(byte), 
            byte = f.read(1)


with open('out.txt','w') as f:
    if __name__ == '__main__':
        f.write(main())
        close.f()

Answer 1

This is a fundamental misunderstanding of what various functions and methods do. You are writing the returned value of main() to the file, expecting main 's print() calls to go to the file. It does not work like that.

def main():
    with open("in.txt", "rb") as f, open('out.txt','w') as output:
        byte = f.read(1)
        while byte != "":
            output.write(str(ord(byte))) 
            byte = f.read(1)

if __name__ == '__main__':
    main()

Use file.write() to write strings (or bytes, if you're using that kind of output, which you currently aren't) to a file. For your code to work, main() would have to return a complete string with the content you wanted to write.

Answer 2

You are calling print ord(byte) from within main() . This prints to the console.

You are also calling f.write(main()) which appears to assume that main() is going to return a value, but it doesn't.

It looks like what you intend to do is replace the print ord(byte) with a statement that appends your desired output to a string, and then return that string from your main() function.

Answer 3

You need to return the string from the function main . You are currently printing it and returning nothing. This will assemble the string and return it

def main():
    with open("in.txt", "rb") as f:
        ret = ""
        byte = f.read(1)
        while byte != "":
            ret = ret + byte 
            byte = f.read(1)
    return ret


with open('out.txt','w') as f:
    if __name__ == '__main__':
        f.write(main())
        close.f()