coder help - what's this ^= ?

[c h u d]

I'm not a crazy-experienced programmer; but I use it for my research. I have some code with equations and I'm trying to determine what they are calculating. This symbol is used as follows: if x ^= 5 then...Anybody know what the ^= would be?

[luthair]

I would think x^5

Which language?

[Rehan]

http://www.google.ca/search?q=c+operators

[c h u d]

http://www.google.ca/search?q=c+operators

Thanks:)