There are many things wrong with this program, please endure while I explain everything:
*) You never set the value of "i", you can't know what its value will be when the first loop starts.
*) Arrays are indexed from 0 to SIZE-1, never attempt to read from or write to above element SIZE-1.
*) You never increment "i" inside the first loop, therefore only a single element ever changes.
*) Arrays don't keep track of their size, you should do that yourself with "value", a variable that you've declared but completely forgot about.
*) Don't use the VS *_s functions, they're non-portable and just a placebo.
*) Don't use system("pause"), your IDE should be able to pause the program by itself. If not, get a better IDE.
You make it harder for yourself by choosing to solve it like that. I suggest an infinite loop with break statements:
Code:
for (;;) {
// Read input
// If input is -999, break
// Save input and increment index
// If index is equal to size, break
}