just brushing up a bit. haven't looked at C code in a while.

pointer_practice.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define INT_MAX 1000
#define UINT_MAX 10

char* getString(void);
int getInt(void);
int* getAge(void);

int main (int argc, char* argv[])
{
  int n;
	if (argv[1] == NULL) 
  {
    printf("proper use: ./pointer_practice <number of dolphins>\n");
		return 1;
	} 
  else 
  {
		n = atoi(argv[1]);
	}

	int* dolphins[n];

	for (int i = 0; i < n; i ++)
	{
		dolphins[i] = getAge();
	}

  int oldest;
  if (n > 0)
  {
	  oldest = *dolphins[0];
  }
  else
  {
    oldest = 0;
  }
	for (int i = 0; i < n; i++)
	{
		if(*dolphins[i] > oldest)
		{
			oldest = *dolphins[i];
		}
	}
	printf("The oldest dolphin is %d!\n", oldest);
}

char* getString(void)
{
  // growable buffer for chars
  char* buffer = NULL;

  // capacity of buffer
  unsigned int capacity = 0;

  // number of chars actually in buffer
  unsigned int n = 0;
  
  // declace placeholder c
  char c;

  // iteratively get chars from standard input
  while ((c = fgetc(stdin)) != '\n' && (c != EOF))
  {
    // grow buffer if necessary
    if (n + 1 > capacity)
    {
      // determine new capacity; start at 32 then double
      if (capacity == 0)
      {
        capacity = 32;
      }
      else if (capacity <= (UINT_MAX / 2))
      {
        capacity *= 2;
      }
      else
      {
        free(buffer);
        return NULL;
      }
      
      // extend buffer's capacity
      char* temp = realloc(buffer, capacity * sizeof(char));
      if (temp == NULL)
      {
        free(buffer);
        return NULL;
      }
      buffer = temp;
    }

    // append current character to buffer
    buffer[n++] = c;
  }

  // return NULL if user provided no input
  if (n == 0 && c == EOF)
  {
    return NULL;
  }

  // minimize buffer
  char* minimal = malloc((n + 1) * sizeof(char));
  strncpy(minimal, buffer, n);
  free(buffer);

  // terminate string
  minimal[n] = '\0';

  // return string
  return minimal;
} 

int getInt(void)
{
  // try to get an int from user
  while (1)
  {
    // get line of text, returning INT_MAX on failure
    char* line = getString();
    if (line == NULL)
    {
      return INT_MAX;
    }

    // return an int if only an int (possibly with
    // leading and/or trailing whitespace was provided
    int n;
    char c;
    if (sscanf(line, " %d %c", &n, &c) == 1)
    {
      free(line);
      return n;
    }
    else
    {
      free(line);
      printf("Retry: ");
    }
  }
}

int* getAge(void)
{
	int* age = malloc(sizeof(int));
	do
	{
		printf("How old is the dolphin (> 0)? ");
		*age = getInt();
	}
	while (*age < 1);

  printf("This dolphin is %d\n", *age);
	return age;
}