help me in c++ calculator

Question

so my problem is I have to make a simple program that will take the users desired arithmetic operation to be used and ask the user how many input he/she want to enter, So the first three operation is quite a bit easy but the division make me sick. can anyone help me? this is my codes by the way

#include <iostream>
using namespace std;

int main() {

int sum,diff,prod = 1,range,StartNum;
char UseOperation;
double num = 1,quo =1;

cout << "Enter Operation to be used : " << endl;
cout << "(a)Addition" << endl << "(b)Subtraction" << endl << "(c)Multiplication" << endl << "(d)Division" << endl;
cin >> UseOperation;

cout << "Enter how many number you want to input : " << endl;
cin >> range;

if (UseOperation == 'a'){
for (StartNum = 0;StartNum < range;range --){
cout << "Enter Number : " << endl;
cin >> num;
num += num;
}
sum = num;
cout << "The sum of the inputed number is " << sum << endl;
}
else if (UseOperation == 'b'){
for (StartNum = 0;StartNum < range;range --){
cout << "Enter Number : " << endl;
cin >> num;
num -= num;
}
diff = num;
cout << "The difference of the inputed number is " << diff << endl;
}
else if (UseOperation == 'c'){
for (StartNum = 0;StartNum < range;range --){
cout << "Enter Number : " << endl;
cin >> num;
prod *= num;
}
prod = prod;
cout << "The product of the inputed number is " << prod << endl;
}
else if (UseOperation == 'd'){
for (StartNum = 0;StartNum < range;range --){
cout << "Enter Number : " << endl;
cin >> num;
num /= num;

}
quo = num;
cout << "The quotient of the inputed number is " << quo << endl;
}
else{
cout << "Error" << endl;
}
return 0;
system("pause");
}

Answer 1

write it on playground to make it easier to read

Answer 2

In case of addition, subtraction and division you have written statements incorrectly.

They should be like:
1) sum += num;
2) diff -= num;
3) quo /= num;

Hope it will solve your issue.

Answer 3

Just in case of division, the quotient will get to zero after three or more inputs.

Let's say at first iteration use enetered number 20.

Second iteration 2
20 / 2 = 10

Third iteration 2
10 / 2 = 5

Fourth iteration 3
5 / 3 = 1

Fifth iteration 4
1 / 4 = 0

So at last you'll get either 0 or 1.

Here notice another thing, at first iteration we are not dividing. We start dividing by 2nd iteration so your code should be like this for division only:

cin >> num;
if(StartNum == 0)
quo = num;
else
quo /= num;

Then print it.
It should work now.

Answer 4

@nAutAxH AhmAd
I have tried what you have suggested it word on addition,subtraction and multiplication but not in division.. maybe Im having logical errors on my codes.. thanks by the way

Answer 5

@nAutAxH AhmAd

it works like magic. thank you very much for the help. I appreciate it so much :)

Answer 6

@ABADA S
I have tried making it in the playground but I always get compile error and I dont know why.

Answer 7

Me too