cout prints the incorrect value

Question

So, I'm trying to make a basic C++ program that converts Base 10 -> Base 16

while(true){
    int input;
    cout << "Enter the base 10 number\n";
    cin >> input;
    cout << "The hex form of " << input << " is: ";
    int decimal = input;
    cout << hex << uppercase << decimal << "\n";
    decimal = NULL;
    input = NULL;
    Sleep(3000);
}

And on the first run through it works. For example, if I enter 7331 I get:

The hex form of 7331 is 1CA3

But if I try it a second time (with the same input) I get:

The hex form of 1CA3 is 1CA3

I can try this with any integer input and it works fine for the first run through but after that it puts the base 16 number in twice.

It's not actually my code, I just wanted to show it was contained in a loop. Let me fix — , Jan 17 '18 at 01:07
Close-voter: what is unclear about this? I find the question to be very clear, OP has mentioned their inputs, outputs and what they expect. The example is more-or-less complete. — Tas, Jan 17 '18 at 01:11
Some stream manipulators are [sticky](https://stackoverflow.com/questions/1532640/which-iomanip-manipulators-are-sticky), some are not. `std::hex` is _sticky_. — Ron, Jan 17 '18 at 01:27

score 3 · Accepted Answer · answered Jan 17 '18 at 01:06

3

You need to reset your stream. When you apply std::hex to std::cout, it applies permanently to the stream (std::cout), and you need to reset it. You can simply change your program to this:

cout << "The hex form of " << std::dec << input << " is: ";

answered Jan 17 '18 at 01:06

Tas

7,023
3
36
51

score 0 · Answer 2 · answered Jan 17 '18 at 01:06

0

your FIX:

cout << "The hex form of "<< dec << input << " is: ";

answered Jan 17 '18 at 01:06

mariusz_latarnik01

649
5
9

sky3 · Answer 3 · 2018-01-17T01:16:12.737

0

You could even shorten your code:

while (true)
{
    int input;

    cout << "Enter the base 10 number: ";
    cin >> input;
    cout << "The hex form of " << dec << input << " is: ";
    cout << hex << uppercase << input << "\n";

    Sleep(3000);
}

edited Jan 17 '18 at 01:16

answered Jan 17 '18 at 01:11

sky3

43
1
6

Yeah, that's how I originally had it. I added the other stuff to try and 'clear' my variables. – Jan 17 '18 at 01:36

cout prints the incorrect value

3 Answers3