The things you use a lot you will naturally memorize, like the structure of a for() loop. Less often used things, like certain string functions, not so much. That's why there are reference materials.
As far as the problem of the moment goes, use descriptive, meaningful variable names. Saving a few keystrokes now with something like 'vc1' will bite you in the a$$ later during troubleshooting - especially as programs grow larger/more complex. Use comments freely. No matter how familiar you become with the code while perfecting it, six months down the road it will be well nigh impenetrable without good comments. A [style guide](C++ Programming Style Guidelines Conventions) is good to have handy too.
p.s. use descriptive variable names