Pls help me experts

Question

I put 1 2 3 enter 4 5 6 enter 7 8 9 in the txt file and read it to char array with read system call. I want to get all the number but the result is
1 2 3 5 6 8 9
what is the problem?
https://code.sololearn.com/cEzG94uGTgkV/?ref=app
https://code.sololearn.com/cEzG94uGTgkV/?ref=app
https://code.sololearn.com/cEzG94uGTgkV/?ref=app