Logically flawed function seems to work?

[atramposch]

I wrote this function for an assignment. It utilizes dynamic memory, which grows and shrinks as needed. I wrote it like this at first:

int user_input (int * array, int intSize)
{
	printf("Please enter any number of integers (80 characters per string max), enter an empty string to signal input completion\n\n");
	
	int i = 0, j = 0;
	int arrayMax = MAXARRAY;
	
	char input[80];
	char * save;
	
	while (input[0] != '\0')
	{
		if (j == arrayMax) 
		{
			arrayMax *= 2;
			realloc_data_up(array, intSize, arrayMax);
		}
		
		printf("->");
		
		i = 0;
		
		while(i < 80 && (input[i] = getchar())!= '\n')
		{
			i++;
		}
		
		input[i] = '\0';
		
		save = strtok(input, " ");
		
		while(save != '\0')
		{
			array[j] = atoi(save);
			save = strtok(NULL, " ");
			j++;
		}
		
	}
		
	realloc_data_down(array, j, intSize);
	
	return j;
}

And it works fine. I tried changing it up to this:

int user_input (int * array, int intSize)
{
	printf("Please enter any number of integers (80 characters per string max), enter an empty string to signal input completion\n\n");
	
	int i = 0, j = 0;
	int arrayMax = MAXARRAY;
	
	char input[80];
	char * save;
	
	while (input[0] != '\0')
	{
		printf("->");
		
		i = 0;
		
		while(i < 80 && (input[i] = getchar())!= '\n')
		{
			i++;
		}
		
		input[i] = '\0';
		
		save = strtok(input, " ");
		
		while(save != '\0')
		{
                 
                        if (j == arrayMax) 
		        {
			           arrayMax *= 2;
			           realloc_data_up(array, intSize, arrayMax);
		        }

			array[j] = atoi(save);
			save = strtok(NULL, " ");
			j++;

		}
		
	}
		
	realloc_data_down(array, j, intSize);
	
	return j;
}

And it gives me an error for pointer not being allocated. Just wondering how the first code works when the second doesnt.

Thanks.