What is the reason of error in the code

Question

It is one of the ques in the c challenge
https://code.sololearn.com/cGgm4P1lJcX0/?ref=app

Answer 1

Try x = {1,2,3};

Answer 2

The syntax only is wrong for that line:
int x=1,2,3;
You can't write like this

Answer 3

https://code.sololearn.com/cpemgbPS90p3/?ref=app

Answer 4

What happenes in this code

Answer 5

Mahv please tell how can you manipulate the values 2 &3 with variable x