Weird Code Issue

Question

So I have a square root calculator in C++. It works great when I enter a number, gives accurate square roots, and so on. But when I don't enter a number into it, it says this:
The square root of 2686816 is 1639.15
Why does it do this and how can I stop it?

I don't know if this is relevant, but I am using #include <cmath> for my square roots.
This is the full code:

#include <iostream>
#include <cmath>
using namespace std;

int main() {
//Initializes 'user_input'
int user_input;
//Defines 'user_input'
cin >> user_input;
//Prints the square root of the user's input
cout << "The square root of ";
cout << user_input;
cout << " is ";
cout << sqrt(user_input) << endl;
cout << "Thank you for viewing my project!" << endl;
int Haha;
Haha = sqrt(5*5*5*5) ;
if (user_input == Haha) {
cout << "Hey, your number," << user_input << ", is my alpha number!" ;
}
return 0;

}

Answer 1

liked your name..@the most awesomest peson..😂made my day👍👍

Answer 2

If you want to prove to yourself that the value comes in with garbage already, put this immediately after "int user_input;"

cout << user_input;

You'll see the preloaded garbage value.

Answer 3

Do a cout of a value before you calculate the sqrt. That will give you an idea of whats happening

Answer 4

Put this in your code: user_input = 0; between initializing and cin. Now it gets some random value out of storage if you don't give a value for input..

Answer 5

Or change this line: int user_input;
to: int user_input = 0;

Answer 6

it's because you didn't initialize the variable try initializing it.
int var(0);
or
std::string ="";
etc.
another good habit is to give it valid initializing variables since here on sololearn people often hit enter not knowing what value to input. this lets them have a valid run their first time and keep interest long enough to learn what input to enter.

Answer 7

Thanks all!

Answer 8

OK I will try that @Dextozz

Answer 9

Wait, How Do I do that?
Do you mean tell it to output my input? When it says The square root of (number input) is (square root), 2686816 is the number that it says is input
So if I enter 25 as the number, it says the square root of 25 is 5.

Answer 10

Hmmm paste your code here. I don't know why that's happening. If you are inputing an int it should say the square root of 0 is 0

Answer 11

Multiple people helped, and everything tried worked. Thanks!!