Using C++ to program, read random contents from a file in the main have been written, requires to a function follow the steps:

encode_string

encode_string(message, payload) ret = "" start = 0; // Encode the payload for every character c in the payload block_length = find_boundary(message, start); if block_length == -1 throw an error block = substring of message starting at start, block_length chars in length append encode_char(block, c) to ret increase start by block_length // Encode a null terminator block_length = find_boundary(message, start); if block_length == -1 throw an error block = substring of message starting at start, block_length chars in length append encode_char(block, '\0') to ret increase start by block_length // Add remainder of message remainder = substring of message starting at start, going to the end of the string append remainder to ret return ret