How long, how many days, does cocaine and heroin stay in someone's system?

Long enough to fail a test, and for hair test...it stays there as long as you have that hair until it grows out.. A significant length of time.

Long term use will show up in even higher concentrations....but Heroine, Morphine and Cocaine are not occasional use drugs.

It depends upon who you ask, but according to the following website: lDrug Testing FAQ's - Tests, Detection Times, and False Positives
The detection time, in urine is the following. I would not take it as gospel, but a reasonable rule of thumb.

Cocaine (benzoyl ecgonine metabolite)	Stimulant	coke, crack, rock cocaine	N/A	Up to 4 days
Codeine	Analgesic / Opiate	N/A	N/A	2 days
Ethyl alcohol, ethanol	depressants / sedatives / hypnotics	alcohol, liquor, beer, wine booze	N/A	urine: 2 to 12 hours serum/plasma: 1 to 12 hours
Heroin	Analgesic / Opiate	smack, tar, chasing the tiger	N/A	2 days