# FAQ: Variables - Review

#include

int main() {
//Weight_Mars (in kg) = Weight_Earth (in kg) x (g_Mars / g_Earth)

``````double weight_earth = 0;

double weight_mars;

const double g_earth = 9.8, g_mars = 0.38 * g_earth;

std::cout << "Enter the weight on Earth :" << weight_earth << "\n" ;

std::cin >> weight_earth;

weight_mars = weight_earth * (g_mars / g_earth);

std::cout << "you Weigh on Mars is: " <<  weight_mars  << "\n";

return 0;
``````

}

#include

int main() {
//Weight_Mars (in kg) = Weight_Earth (in kg) x (g_Mars / g_Earth)

``````double weight_earth = 0;

double weight_mars;

const double g_earth = 9.8, g_mars = 0.38 * g_earth;

std::cout << "Enter the weight on Earth :" << weight_earth << "\n" ;

std::cin >> weight_earth;

weight_mars = weight_earth * (g_mars / g_earth);

std::cout << "you Weigh on Mars is: " <<  weight_mars  << "\n";

return 0;
``````

}

Hi there

so I didn’t enter any value for miles and It kind of went through, help!

#include

int main() {

double weightEarth;

double weightMars;

std::cout << "Enter how much weight It on earth : ";

std::cin >> weightEarth;

weightMars = (weightEarth/9.81)*3.711;

std::cout <<“Your weight in Mars is “<<weightMars<<”\n”;

double miles;

double kilometers;

std::cout <<"Now enter a distance in miles: ";

std::cin >> miles;

kilometers = miles*1.609344;

std::cout << kilometers<<" Kilometers\n";

}

You have `64,5`
… try that without the `,`
I think it’ll only accept decimals using `.` anyway: `64.5`

1 Like

Thanks! It worked!     can anyone help me with this code?
weight is 45 kg and if i at mar, my weight will be “weight * 37.83 / 100 = 17.0235” but my code ouput is -3.87569e+08 kg

``````#include <iostream>

int main() {
int weight;
float weightmar = weight * 37.83 / 100;
std::cout << "ur weight is: \n";
std::cin >> weight;
std::cout << "ur weight at mar is: " << weightmar << " kg" << std::endl;
}
``````

Your statements will be executed top to bottom.

You are declaring the `weight` variable and then using it to calculate `weightmar`. But, at this point, `weight` is uninitialized.

An uninitialized variable will result in undefined behavior (in your case it happens to be garbage/nonsense output).

Then, you prompt the user for input and assign it to `weight`. But, your calculation for `weightmar` has already been performed, so this input value doesn’t make a difference.

Instead you should consider re-arranging your code so that you get and assign the user input to `weight` first and then perform the calculation for `weightmar`.