I am trying to make a finals grade calculator, but it isn't working

Question

C++ beginner here. So, I'm trying to make this code function like a finals grade calculator, but it isn't working. It gives back the value of 100 every time. What's wrong?

#include <iostream>

using namespace std;

int main()
{
    double grade, des, worth, per, grade1, tgrade, fgrade;
    cout<<"What is your current grade in the class?"<<endl;
    cin>>grade;
    cout<<"What is your desired grade in the class?"<<endl;
    cin>>des;
    cout<<"How much is your final exam worth? (Percent of total grade)"<<endl;
    cin>>worth;
    per=1-(worth/100);
    grade1=grade*per;
    fgrade=100;
    while ((tgrade-0.01)<=des<=(tgrade+0.01)) {
        fgrade=fgrade-1;
        tgrade=grade1+(fgrade*(worth/100));
    }    
    cout<<"You need a grade of "<<fgrade<<"% on your final exam to reach your desired grade in your class. Good Luck!"<<endl;
    return 0;
}

Does this answer your question? [Double inequality while comparying three floating point numbers](https://stackoverflow.com/questions/34389221/double-inequality-while-comparying-three-floating-point-numbers) — Aykhan Hagverdili, Dec 13 '19 at 05:30
`grade1` is only assigned to and `per` is only used to calculate it. — AndersK, Dec 13 '19 at 05:57

score 0 · Answer 1 · answered Dec 13 '19 at 05:26

0

I can see the logic you're trying to achieve in the loop condition, however <= is a binary operator, so you need to have two conditions which you combine with &&.

while((tgrade-0.01) <= des && des <= (tgrade+0.01))

answered Dec 13 '19 at 05:26

robthebloke

9,331
9
12

1

Additionally, `tgrade` is never initialized before that use, so the loop will misbehave anyway. – Joachim Isaksson Dec 13 '19 at 05:28
I did what you said, but it still returns a value of 100 when I try it. Also, @JoachimIsaksson how do you recommend I initialize it? – bmgballer Dec 13 '19 at 05:42

I am trying to make a finals grade calculator, but it isn't working

1 Answers1