What do you mean by "in c"? There are additional programs that can be used to calculate HWE - hwsnp for instance. You need to install them into the main program. 

Dear TIna

Thank you for the reply it was "case control studies" and now i have corrected the question.

Check the Econometrics textbook by Chris Baumol, it is full of Stata commands and various methodologies.

Dear GariKai

Thank you for the answer. At the same  time I would like to request you if you could provide me the e-copy  of this book  (if possible) as it is not available with me.

Hi! Just came across this question here. It has been a few years since this was posted but it might help new visitors!

STATA has 2 commands for hardy weinberg equilibrium calculations: hwsnp and genhw. Both are user written commands and have to be installed. You can do that using the help command.

hwsnp is a quick command that can be used on SNPs that are in the genotype format (AA, GG, AG etc) and gives pearson's chi p-value, LR test p-value and an exact test p-value. For those SNPs where all 3 variants of the genotype are not present in the population (eg: out of AA, GG and AG, only 2 are present out of 3), the hwsnp command breaks, i.e. it doesnt give a p-value for those SNPs. In that case, you need to break the genotype into single alleles (AG broken into A and G in two separate variables) and run the genhw command on the two allele variables for that SNP.