C - read TXT change from dup to fgets and sscanf - c

Question

I read from txt pairs of numbers
How check it only 2 numbers in each line and not 3. I want show the line is the problem for example the pairs file:
3
25 35
14 42
30 60 70
Console: illegal input at line 4
I know That's not the correct way at all. Need use fgets to read and sscanf to parse.
I tried but the memory full garbage. How can I change it correctly?
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char *argv[])
{
int i, c;
FILE *fp;
char str[100];
fp = fopen("./pairs.txt", "r");
if (dup2(fileno(fp), STDIN_FILENO < 0))
{
printf("Error opening file");
return -1;
}
if (feof(fp))
printf("Error reading file");
scanf("%d", &numOfPairs);
arrNum = (int *)malloc(sizeof(int) * numOfPairs * numbersInPair);
for (int i = 0; i < numOfPairs * numbersInPair; i += 2)
{
int num1, num2;
scanf("%d %d", &num1, &num2);
arrNum[i] = num1;
arrNum[i + 1] = num2;
}
}
Another try NOT working:
int main(int argc, char *argv[])
{
int index, i, numOfPairs;
int c;
FILE *file;
file = fopen("./pairs.txt", "r");
if ((c = getc(file)) == EOF)
{
perror("Error opening file"); //or return 1;
fclose(file);
}
while ((c = getc(file)) != EOF)
putchar(c);
{
fscanf(file, "%d", &numOfPairs);
allNumbers = (int *)malloc(sizeof(int) * numOfPairs * numbersInPair); //need multiply in 2 numbers for each pair
while (!feof(file) && numOfPairs > 0)
{
int x, y, arrIndex = 0;
numOfPairs--;
fscanf(file, "%d %d", &x, &y);
allNumbers[arrIndex] = x;
printf("The X : %d\n", x);
allNumbers[arrIndex + 1] = y;
printf("THE Y : %d\n", y);
arrIndex + 2;
}
fclose(file);
}