将霍夫曼代码输出到文件

Question

I have a program that reads a file and saves the frequency of each character. It then constructs a huffman tree based on each character's frequency and then outputs to a file the huffman codes for the tree.

So an input like "Hello World" would output this sequence to a file:

01010101 0010 010 010 01010 0101010 000 01010 00101 010 0001

This makes sense because the most frequent characters have the shortest codes. The issue is, this increases the file size ten-fold. I realized the reason why is because each 1 and 0 is being represented in memory as its own character, so they get each get expanded out to a byte of data.

I was thinking what I could do is convert each code (EG "010") to a character and save that to file - but that still would pad the code to be a byte long (Or mess it up if the code is longer than a byte).

How do I go about this? I can give code snippets if needed - I'm basically saving each code into a string so that's why the file's coming out so big (It's outputting each "bit" as a byte). If I were to convert the code to a long for example, then a code like 00010 would be represented as 2 and a code like 010 would also be represented as 2.

Answer 1

You basically have to do it a byte (or a word) at a time. Maintain a byte which you fill with bits, and a record of how many bits have been filled in so far. When you get to 8, write the byte and start over with an empty one.