You could use the string library, and append each character to a string.
Then, use indexOf() to locate each <. Extract the rest of the string as a new string, overwriting the old string. Use startsWith() to see if the string starts with "body".
When it does, extract a substring starting at 5 (right after the >). Then locate the next < (in . The substring of interest then starts at 0 and ends just before the <.
Use itoa to convert the extracted string to an integer that will be either 0 or 1, after leading and trailing spaces are ignored.
Alternatively, you could change the PHP script so that instead of writing 0 or 1, it wrote "Entre vous" or "Stay the f**k out" (or whatever strings seem appropriate to you), and then use contains() to see if either of those strings are contained in the body of the message.