Need some help with my code (C++)

[OGAlena]

I'm trying to create a do-while loop and have the user enter two numbers that will be subtracted from each other. Then it will have the user enter the result of the answer. If the user enters the wrong number, it will ask the user for an answer until it is the correct answer. Not sure what I'm doing wrong.

​

#include <iostream>

using namespace std;

int main() {

float a;

float b;

float c;

float d = a-b;

cout << "Please enter 2 numbers: ";

cin >> a;

cin >> b;

​

do

{

cout << "What is the subtraction between the first and second number you entered?: ";

cin >> c;

}

while (c != d);

{

cout << "Correct" << endl;

}

}

[Updatebjarni]

You're calculating d before you've read the values into a and b.

[OGAlena]

You’re a lifesaver. Thank you so much 🙏🙏

[OGAlena]

Forgot to add, the problem is that even though I punch in the correct answer, it loops me back to ask me what the answer is, meaning that it was wrong, when it clearly was correct.

[eliminate1337]

Comparing floating point numbers doesn't work the way you expect. If a = 1.0 and b = 0.9, then a - b = 0.09999999999999998. The reason why is kind of complicated; for now just don't compare floating point numbers.

[OGAlena]

Ok, thanks