Right, starting to feel a little embarrassed now...
read_numbers is returning size nicely into the print_numbers function, but in trying to get fscanf to work, which I presumed I needed a loop for, the loop seems to refuse to function like a for loop has every other time I've used one...
I thought when it ran that it would iterate from 0 to size, but I've put a printf in there to print i as it does and nothing appears!
This is probably something entirely stupid and small so I apologist for that, but here's my broken code:
void print_numbers(FILE *fptr, int numbers, size_t size)
int max_size=100, i=0;
size=read_numbers(fptr, numbers, max_size);
printf("Values contained within TXT File:\n\n");
for(i=0; i==size; i++)
fprintf(fptr, "Number %d. %d\n",i, numbers);