Aw yes, that's the VLA (Variable length array). It is working it's way up the ladder, and will be a standard part of C, "soon".
Some compilers have this feature already, but my old workhorse, doesn't! < cry >
Until yours does, the only way to enlarge an array is by making it dynamic, and malloc()'ing what you need (or realloc() if you have already malloc'd the memory.
The general way to handle this in a practical and easy manner, is to size your array, LARGE, and then use only what you need. Then count the number of good elements that have data, and use the array, like it was just that size:
Code:
for(i=0;i<size of my data, not th size of the array; i++)
printf("%d", arrayName[i]);