pow!

/* index of po2 works as follows:
	po2[0] is base ^ 2^0
	po2[1] is base ^ 2^1
	po2[2] is base ^ 2^2
	...
	po[i] is base ^ 2^i
*/
int power(int base, int exp) {

	int n = (exp+1)/2;
	int *val = calloc(n,sizeof(int));
	int *po2 = calloc(n,sizeof(int));
	val[0] = 1;
	po2[0] = 1;
	val[1] = base*base;
	po2[1] = 2;
	int i;
	int expCounter = exp;
	int result = 1;
	for(int j = 2; j < n; ++j)
	{
		val[j] = val[j-1] * val[j-1];
		po2[j] = po2[j-1] * po2[j-1];
	}
	i = n - 1;
	while(expCounter > 0)
	{
		if(expCounter % 2 == 0)
		{
			if(expCounter - po2[i] >= 0)
			{
				result*=val[i];
				expCounter-=po2[i];
			}
			--i;
		}else
		{	
			result*=base;
			--expCounter;
		}
	}
	free(val);
	free(po2);
	return result;
}

pow.c

/* index of po2 works as follows:
	val[0] is base ^ 2^0
	val[1] is base ^ 2^1
	val[2] is base ^ 2^2
	...
	val[i] is base ^ 2^i
*/
int power(int base, int exp) {

	int *val = malloc(sizeof(int));
	int *po2 = malloc(sizeof(int));
	val[0] = 1;
	po2[0] = 1;
	val[1] = base*base;
	po2[1] = 2;
	po2[2] = 4;
	int i = 2;
	int expCounter = exp;
	int result = 1;
	do
	{
		val = realloc(val,i*sizeof(int));
		val = realloc(val,(i+1)*sizeof(int));
		val[i] = val[i-1] * val[i-1];
		po2[i+1] = po2[i] * po2[i];
		++i;
	}while(expCounter - po2[i] >= 0);
	
	while(expCounter > 0)
	{
		if(expCounter % 2 == 0)
		{
			if(expCounter - po2[i] >= 0)
			{
				result*=val[i];
				expCounter-=po2[i];
			}
			--i;
		}else
		{	
			result*=base;
			--expCounter;
		}
	}
	free(val);
	free(po2);
	return result;
}