Pointer to Pointers Sample & Out Parameter Sample

PointersToPointers.c

#include <stdio.h>

/********************************************
*  Function         : MinMax                *
*  Input parameters : *begin, *end          *
*  Output parameters: **smallest, **largest *
********************************************/
int minMax(int * begin,
            int * end,
            int ** smallest,
            int ** largest)
{
	printf("[minMax]...minMax function started\n");
	
	if(begin && end)
	{
		if (begin == end)
		{
			*smallest = 0;
			*largest = 0;
			
			printf("[minMax]...No range, function halted\n");
			return -1;
		}
		else
		{
			*smallest = *largest = begin;
			
			for(; begin != end; ++begin)
			{
				if( *begin < **smallest)
				{
					*smallest = begin;
				}
				
				if( *begin > **largest)
				{
					*largest = begin;
				}
			}
		}
	}
	else
	{
		printf("[minMax]...input parameters must not be NULL, function halted\n");
		return -1;
	}
	
	printf("[minMax]...minMax function ended\n");
	return 0;
}

/********************************************
*  Function         : printArray            *
*  Input parameters : *array                *
*  Output parameters: N/A                   *
********************************************/
void printArray(int *array, int size)
{
	if(array)
	{
		printf("array : ");
		for(int i = 0; i != size; i++)
		{
			printf("%2d ", array[i]);
		}
		printf("\n");
	}
	else
	{
		printf("[printArray]...array is NULL, function halted\n");
	}
}

int main()
{
	printf("****************************************************\n");
	int value = 123;	/* an integer */
	int *p = &value;	/* pointer pointing to an int */
	int **pp = &p;		/* pointer to pointer which is pointing to an int */
	
	printf("integer value                    : %d\n", value);
	printf("content of pointer               : %d\n", *p);
	printf("content thru the pointer pointer : %d\n", *(*pp));
	printf("double dereferencing of pp       : %d\n", **pp);
	
	printf("****************************************************\n");
	int values[] = { 5, 1, 3, 2, 9, 0 };
	int size = sizeof(values) / sizeof(values[0]);
	printArray(values, size);
	
	int * smallest = 0;
	int * largest = 0;
	
	
	int err = minMax( values,
                      values + size,
                      &smallest,
                      &largest);
	
	if(!err)
	{
		printf("Smalest number in the array      : %d\n", *smallest);
		printf("Largest number in the array      : %d\n", *largest);
	}
	
	return 0;
}