How to calculate a/b in C++?

Question

I am trying to get value for a/b, but I always get '0' for a/b.

Why do I get a/b=0 ?

#include <iostream>
using namespace std;

int main()
{
  int a,b;
  cout << "Give a and b" << endl;
  cin >> a >> b;
  double q=a/b;
  cout << "a/b=" << q;
  return 0;
}

@Laurel but I used double for q, shouldn't that make difference? — user40, Oct 18 '16 at 22:19
@user40 no. `a/b` is executed first, and its result (which is an integer) is assigned (and converted to) `q` after that. — krzaq, Oct 18 '16 at 22:19
At least cast one operand to `double` to avoid integer division: `double q=a/(double)b;` — πάντα ῥεῖ, Oct 18 '16 at 22:21

Remy Lebeau · Accepted Answer · 2016-10-18T22:26:08.623

You are using integer arithmetic, so the division result will be an integer. A floating point value that is between 0 and 1 will get truncated to 0 when interpretted as an integer, before it is assigned to your q variable. So either:

change your a and b variables to double instead of int
typecast a and/or b to double during the division.

Either way, you will then be performing floating-point division instead of integer division, so the result will be a floating-point value.

score 1 · Answer 2 · answered Oct 18 '16 at 22:21

1

Can do double q=double(a)/b; instead.

answered Oct 18 '16 at 22:21

grigor

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How to calculate a/b in C++?

2 Answers2