you are passing an array to both of your push and pop function(as 1st argument) but wrongly defined them as double in their function prototypes as well as definition.
Also main returns int.
However the error you are getting seems to be weird though.
Edit:
Which compiler are you using?
I think the error might be because the declarations should be made first.
try moving your
below and see if the error goes.Code:ptr=&stackSize;
