Difficulty with Do/While Loop

[notMarcoScutaro]

Hello all. I am attempting to write a program that will generate a random number after entering 'y' or 'Y' when prompted. In each implementation, the program should first ask the user if they want to generate a random number, then if they answer ‘y’, generate and display a random number, otherwise exit.

Unfortunately, the program is sending back random numbers regardless of which key I hit, and not exiting at all. Any help with whatever I am missing here would be greatly appreciated. I will continue troubleshooting as well. Thank you.

#include <iostream>
#include <string>

using namespace std;
int main()
{
   char generate;
   double number =static_cast<double>(rand()) / RAND_MAX;

   do
   {
      cout << "Do you want to generate a random number? (Enter 'y' for yes or 'n' for no.)" << endl;
      cin >> generate;
   }  
      while (generate=='y' || generate=='Y');
      cout << "Random number: " << number << endl;
      
   system("pause");
   return 0;
}

[Moschops]

It does exactly what you programmed it to do.

Look at the do-while loop. What is inside it? Getting input from the user. That's it. So that loop will go around and around, doing nothing apart from getting an input from the user.

Where is the output of the random number? After the loop. So once the user says "n", you get out the random number and the program finishes.

[hjone]

You have a semi-colon at line 15 that should not be there.

Oops my bad. I never use do-while loops. Personal preference, I just hate them.

[ryancb06]

You have a semi-colon at line 15 that should not be there.

That is the appropriate form of do{}while(); loops!

[notMarcoScutaro]

I see. Would it have been better to use a different type of loop then? I'm also not very clear on outputting the random number. Thank you for your replies.

[hjone]

If you only want to ask them once I would have done it this way:

cout << "Do you want to generate a random number? (Enter 'y' for yes or 'n' for no.)" << endl;
cin >> generate;
if (generate=='y' || generate=='Y')
cout << "Random number: " << number << endl;

If you want to keep generating random numbers until they say no I would do:

cout << "Do you want to generate a random number? (Enter 'y' for yes or 'n' for no.)" << endl;
cin >> generate;
while (generate=='y' || generate=='Y')
{
      number = static_cast<double>(rand()) / RAND_MAX;
      cout << "Random number: " << number << endl;
      cout << "Do you want to generate another random number? (Enter 'y' for yes or 'n' for no.)" << endl;
      cin >> generate;
}

[TheIdeasMan]

Also, if you make use of the std::toupper function, you can avoid testing the value of the generate variable twice.

cin >> generate;

generate = std::toupper(generate);

while (generate=='Y') {
//your code
}

hjone wrote:

I never use do-while loops. Personal preference, I just hate them.

Me too. Unless I really need to.