int j = 0; for(int i = 0;i<n;i++){j++;}

This is an incomplete for loop as there is no increment/decrement statement for i. It will result in an infinite loop. The correct syntax should be:

int j = 0; 
for(int i = 0; i < n; i++){
    j++; //or any other statement
}

In this updated for loop, the variable i is incremented by 1 in each iteration until it reaches the value of n, and the variable j is incremented by 1 in each iteration as well.