working of if else in c++ language

Question

 #include <iostream>
 using namespace std;
 int main()
 {
int n;
cin >> n;
if( 1<=n<=9)
    {
    switch(n)
        {
    case 1:cout<<"one"; break;
    case 2:cout<<"two"; break;
    case 3:cout<<"three"; break;
    case 4:cout<<"four" ;break;
    case 5:cout<<"five" ;break;
    case 6:cout<<"six" ;break;
    case 7:cout<<"seven"; break;
    case 8:cout<<"eight" ;break;
    case 9:cout <<"nine";

    }
  }
  else
    { cout<<"greater than nine"; }

}

the above code when i am running (or)compiling my else statement is not working for example if i am giving a number like 44 it is not displaying the statement in else that it is grater than nine but the if case is working nicely.

The expression `1<=n<=9` is equal to `(1 <= n) <= 9`, which means you compare a boolean value (the result of `1 <= n`) with a number. — Some programmer dude, May 18 '17 at 15:52
`1<=n<=9` is not the correct way to specify multiple boolean conditions. You need `&&` like in most languages. — AndyG, May 18 '17 at 15:52
Welcome to Stack Overflow! Sounds like you could use a [good C++ book](http://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list) — NathanOliver, May 18 '17 at 15:53
where you have "if (1 <= n <= 9)", you need to change it to something that will actually do what you want. — E.D., May 18 '17 at 15:54
"1 <= n <= 9" is equivalent to "(1 <= n) <= 9". if n = 44, then first we evaluate (1 <= 44), which evaluates to 1, so then we evaluate 1 <= 9, which evaluates to 1. — E.D., May 18 '17 at 15:55
ya i understood now , i am new to programming so i got confused — Nikhil Sai, May 18 '17 at 16:02
Your condition should be like this if (n >= 1 && n <= 9) if you'are new with programming language and you don't know how to properly make a condition you can use this link / web site to learn http://www.cprogramming.com/tutorial/lesson2.html This lesson will help you to learn how to make a condition — Hicham Bouchilkhi, May 18 '17 at 16:04

score 3 · Accepted Answer · answered May 18 '17 at 15:54

3

You have a problem with your if condition.

It should be like this:

if (n >= 1 && n <= 9)

As it is now, it means

if ((1 <= n) <= 9)

Which will always evaluate to true.

answered May 18 '17 at 15:54

Federico klez Culloca

26,308
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score 1 · Answer 2 · edited May 18 '17 at 16:26

1

Try changing the condition to

if (1<=n && n<=9)

edited May 18 '17 at 16:26

Ðаn

10,934
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95

answered May 18 '17 at 15:56

Rafed Muhammad Yasir

439
8
16

you made a mistake in your condition it's should be if (n >= 1 && n <= 9) – Hicham Bouchilkhi May 18 '17 at 15:59
`n >= 1` and `1 <= n` are equivalent. The latter condition might be more readable, because it resembles the mathematical form. `1<=n && n<=9` requires *looking* at it to understand, while `n >= 1 && n <= 9` requires *reading*. The readability difference is small and, I suspect, subjective. – anatolyg May 18 '17 at 16:06
@Esperadoce There's nothing wrong with the condition in this answer. – Blastfurnace May 18 '17 at 16:08
I was just showing how to write the conditions properly. Making it better or more readable was not my intention. – Rafed Muhammad Yasir May 18 '17 at 16:11
@Blastfurnace regarding Nikhil Sai question it's a false answer – Hicham Bouchilkhi May 18 '17 at 16:25

working of if else in c++ language

2 Answers2