Error in displaying the largest and smallest number

Question

I was attempting to write a program for exercise 2.19 in How to Program, but I ran into some difficulties.

The program is supposed to have the user enter three integers and then display the sum, average, and product of those integers.

The only problem I am having is with displaying the largest and smallest. When I ran the program and entered three integers (8, 9, and 10), the output read Smallest is 8 AND Smallest is 9.

I was hoping you could tell me why.

#include <iostream>
using namespace std;

int main ()
{   int x, y, z, sum, ave, prod;

    cout << "Input three different integers ";
    cin >> x >> y >> z;

    sum = x + y + z;
    cout << "\nThe sum is " << sum;

    ave = (x + y + z) / 3;
    cout << "\nThe average is " << ave;

    prod = x * y * z;
    cout << "\nThe product is " << prod;

    if (x < y, x < z)
      {cout << "\nSmallest is " << x;}

    if (y < x, y < z)
      {cout << "\nSmallest is " << y;}

    if (z < x, z < y)
      {cout << "\nSmallest is " << z;}

    if (x > y, x > z)
      {cout << "\nLargest is " << x << endl;}

    if (y > x, y > z)
      {cout << "\nLargest is " << y << endl;}

    if (z > x, z > y)
      {cout << "\nLargest is " << z << endl;}

    return 0;
}

P.S. I am doing this to study, this is not homework.

`&&` is the logical AND. `||` is the logical OR. – David G Sep 22 '12 at 20:34 — David G, Sep 22 '12 at 20:34

Mahmoud Fayez · Accepted Answer · 2012-09-22T20:44:54.027

7

You need to rewrite this if condition

if (x < y, x < z)

to be

if (x < y && x < z)

and do the same for all of the remaining if conditions you have.

Edit: All experssions seperated by comma will be evaluated so if you have something like that x = 5, y = 6; it will evaluate both of them and set x to 5 and y to 6 but z = (x=5, y=6); this will cause z to be set to 6 just like y as y=6 was the last term in the list of comma separated terms.

edited Sep 22 '12 at 20:44

answered Sep 22 '12 at 20:25

Mahmoud Fayez

3,398
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Thanks a lot! I know to use && now. – user1691432 Sep 22 '12 at 20:42
I have added more details to help you understand why it was not working with commas, please check this sample code I wrote for your: http://codepad.org/sknsEk3i – Mahmoud Fayez Sep 22 '12 at 20:46

score 3 · Answer 2 · answered Sep 22 '12 at 20:43

int main() {

  std::cout << "Enter three numbers: ";

  int sum = 0;
  double avg = 0.;
  int product = 0;
  int smallest = std::numeric_limits<int>::max();
  int largest = std::numeric_limits<int>::min(); // the initializers here might not be correct, but the gist is in place...

  for (int i = 0; i < 3; ++i) {
    int val = 0;
    std::cin >> val;

    sum += val;
    avg += val;
    product *= val;

    if (val < smallest) smallest = val;
    if (val > largest) largest = val;
  }
  avg /= 3.; // This can also be done in the for loop, I just forget how.

  std::cout << "Sum: " << sum;
  // etc...  The calculations are all done.
}

score 1 · Answer 3 · answered Sep 22 '12 at 20:25

Replace your commas, with && for an AND operator, meaning both of the conditions have to be true, or || which is an OR operator, if you want any or both conditions to be satisfied.

from C++ docs:

The comma operator (,) is used to separate two or more expressions that are included    
where only one expression is expected. When the set of expressions has to be evaluated 
for a value, only the rightmost expression is considered.

score 1 · Answer 4 · edited May 27 '13 at 17:09

1

Use && in place of , inside your if conditions.

edited May 27 '13 at 17:09

Taryn

242,637
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answered Sep 22 '12 at 20:26

harry4

189
1
4
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score 1 · Answer 5 · answered Sep 22 '12 at 20:31

1

Instead of comma, you want && i.e.

if (x < y , x < z)
  {cout << "\nSmallest is " << x;}

should be

if (x < y && x < z)
  {cout << "\nSmallest is " << x;}

answered Sep 22 '12 at 20:31

John Jorsett

276
2
8

score 0 · Answer 6 · answered Sep 22 '12 at 20:37

0

By now you realize that && is for AND and that you should use this operator instead of the comma, ,. But did you know you can also use they keyword and in place of its symbol equivalent?:

if ( x < y and x < z ) {

}

answered Sep 22 '12 at 20:37

David G

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Error in displaying the largest and smallest number

6 Answers6