Output writing – If-else with post/pre increment – Computer Sir Ki Class


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Solved Problem #CPP#2014 siteicon   siteicon   siteicon  

Problem Statement - Output writing – If-else with post/pre increment

Write the output of the following c++ program when the user input value are -1 and 1.

int main()
  int n;
  cout<<"Enter and integer :";
  if(n++ >= ++n)
    cout<<n<<" if";
    cout<<++n<<" else";
  return 0;


TC++ #2014


Run Output

Enter and integer :-1
1 else

Enter and integer :1
3 else


if(n++ >= ++n) cout<<n<<” if”;
If n is 1 then value before >= will be 1 itself as it is a post increment operator. The value after >= will be 2, so the condition will be false and the value of n will become 2 as soon as this expression is evaluated.

else cout<<++n<<” else”;
Since it will reach the else condition as if expression was evaluated as false. Now if the input was 1 it will reach here as 2 and with the pre-increment as ++n it will become 3. Similarly if the initial input is -1 it will become +1 (+1 is two increments ahead of -1).

Common Errors

  • Many students forget to pre-increment value in the if expression comparison.


sunmitra| Created: 29-Dec-2017 | Updated: 18-Dec-2018|

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