C++ little question

Applications Programming
1

Hi,

I am doing a C++ self-study and I got stuck with this problem.
I want to have a code that asks the suer to enter two numbers and then it lists the numbers between these two numbers. It has also to print a message if these two numbers are equal.
Here is what I wrote:

#include <iostream>

int main()
{
  int i, j;
  std::cout << "Enter two numbers:" << std::endl;
  std::cin >> i >> j;
  std::cout << "You etered: " << i << " and " << j << "!" << std::endl;
  
  if (i=j)
    std::cout << "They are equal" << std::endl;
  else {
    if (i<j) {
      std::cout << i << std::endl;
      ++i;
    }
    else if (i>j) {
      std::cout << j << std::endl;
      j++;
    }
  }  
  return 0;  
  
}

I have also tried many alterations using while and for statements. My question is: Why it does stuck at the first if statement, and then quits?

Thanks,

faizlo

2

change

if (i=j)
    std::cout << "They are equal" << std::endl;
  else {

to

if (i==j)
{
    std::cout << "They are equal" << std::endl;
}
  else {

------------------------

== is the comparison whereas = is used to set

3

I did the following:


#include <iostream>

int main()
{
  int i, j;
  std::cout << "Enter two numbers:" << std::endl;
  std::cin >> i >> j;
  std::cout << "You etered: " << i << " and " << j << "!" << std::endl;
  
  if (i==j)
    std::cout << "They are equal" << std::endl;
  else {
    for (i, j; i<j; i++) {
      std::cout << i << std::endl;
      ++i;
    }
    for (i, j; i>j; j++) {
      std::cout << j << std::endl;
      j++;
    }
  }
  
  return 0;  
  
}

Still, I am not getting the right answer!

~faizlo

4

I would nest the if statement in {} brackets, not sure if that matters, probably me being OCD :stuck_out_tongue:

Anyway, you cannot be certain that the first number is smaller that the second number entered, so i would do something like this..

int x, y;
if (i==j)
{
    std::cout << "They are equal" << std::endl;
}
else {
     if( i > j)
     {
       x = j;
       y = i;
     }
      else {
          x = i;
          y = j;
      }

      //now you x and y (x being the smallest number)

      for(x; x < y; x++)
      {
        std::cout << x << std::endl;
       }

code might not be 100% but you should get the idea, will make life easier knowing the smallest number

5

Hi again and thank you all.

Here is what I tried. Since I have two numbers and better than speculating which is which, I tried this:

#include <iostream>
 
int main()
{
  std::cout << "Please specify two natural numbers:" << std::endl;
  int i, j, k;
  std::cin >> i >> j;
 
  if (i >= j)
    {
      k = j;
      j = i;
      i = k; 
     }
 
      for (int x = i; x <= j; ++x) std::cout << x << " ";
 
      std::cout << std::endl;
 
  return 0;
}

Still, I do not know why my second posted code (the one with if ( i==j ) ) doesn't work?
No matter what the two numbers are, it prints the message that the two numbers are equal!

~faizlo

6

It works for me... Maybe you forgot to recompile it after editing. Or are compiling the wrong file.

7

Hi Again,

Corona688, I have compiled it again, and I tried it again, as in post 3, here is what I got:

faizlo@faizlo-laptop:~/C++_tut$ ./range 
Enter two numbers:
10
12
You etered: 10 and 12!
10
faizlo@faizlo-laptop:~/C++_tut$ ./range 
Enter two numbers:
10
20
You etered: 10 and 20!
10
12
14
16
18
faizlo@faizlo-laptop:~/C++_tut$

Any clue!?

~faizlo

8

If you want to print all the numbers between the first and second including the first and second the following will work

#include <iostream>

int main()
{
   int i, j;

   std::cout << "Enter two numbers: " << std::endl;
   std::cin >> i >> j;
   std::cout << "You entered: " << i << " and " << j << "!" << std::endl;

   if (i==j)
      std::cout << "They are equal" << std::endl;
   else {
      for (; i <= j; i++) {
         std::cout << i << std::endl;
      }
   }

   return 0;
}

If you want to print all the numbers but exclude the first and second:

#include <iostream>

int main()
{
   int i, j;

   std::cout << "Enter two numbers: " << std::endl;
   std::cin >> i >> j;
   std::cout << "You entered: " << i << " and " << j << "!" << std::endl;

   if (i==j)
      std::cout << "They are equal" << std::endl;
   else {
      for (++i; i < j; i++) {
         std::cout << i << std::endl;
      }
   }

   return 0;
}

If you want to handle the case where the first number inputted is greater than the second number:

#include <iostream>

int main()
{
   int i, j;

   std::cout << "Enter two numbers: " << std::endl;
   std::cin >> i >> j;
   std::cout << "You entered: " << i << " and " << j << "!" << std::endl;

   if (i==j)
      std::cout << "They are equal" << std::endl;
   else {
      if (i > j) {
        int t = i;
        i = j;
        j = t;
      }
      for (++i; i < j; i++) {
         std::cout << i << std::endl;
      }
   }

   return 0;
}
9

You are using a conditional if() statement and not a loop, some changes and it works

 
#include <iostream.h>
int main()
{
  int i, j;
  cout << "Enter two numbers:" << endl;
  cin >> i >> j;
  cout << "You etered: " << i << " and " << j << "!" << endl;
  
  if (i==j)
    cout << "They are equal" << endl;
  else
  {
    if (i<j)
     {
      while(i < j)
       {
       cout << i << endl;
       ++i;
       }
     }
    else if (i>j) {
     while(i > j)
      {
      cout << j << endl;
      j++;
      }
    }
  }
  return 0;
10

Thank you so much.
I am happy I am here in this forum!

---------- Post updated at 03:51 AM ---------- Previous update was at 03:46 AM ----------

fpmurphy

What does this for statement mean:

for (++i; i < j; i++)

?

11

a loop to iterate through user given range excluding first (++i) element and last element (i < j).

12

++i is a so clever idea, then!

Thank you so much all again.