Final answer:
The expected code length affects the efficiency of encoding blocks of symbols. Shorter code lengths result in more efficient encoding because they require fewer bits to represent each symbol. Variable-length codes, such as Huffman coding, optimize the expected code length to minimize the total number of bits needed.
Step-by-step explanation:
When encoding blocks of symbols, the expected code length refers to the average length of the codes used to represent those symbols. The effect of expected code length is that shorter code lengths result in more efficient encoding. This is because shorter code lengths require fewer bits to represent each symbol, leading to a smaller overall encoded size.
For example, let's say we have a block of symbols and we use a fixed-length code where each symbol is represented by the same number of bits. In this case, the expected code length is equal to the fixed length. However, if we use variable-length codes, where symbols can be encoded with different lengths, the expected code length can be optimized to minimize the total number of bits needed.
To demonstrate this, consider Huffman coding, which is a commonly used variable-length encoding technique. Huffman coding assigns shorter codes to more frequently occurring symbols and longer codes to less frequent symbols. This optimizes the expected code length and reduces the overall encoded size.