C++ Converting a while loop to a do-while loop - c++

Question

I see a ton a questions for converting for loops to while and do while loops, but I cant seem to find anything on converting while loops to do while loops in C++. It still needs to maintain the same function as the original code as well.
Here is the original code:
int number, product = 1, count = 0;
cout << "Enter a whole number to be included in the product"
<< endl << "or enter 0 to end the input: ";
cin >> number;
while (number != 0)
{
product = product * number;
count++;
cout << "Enter a whole number to be included in the product"
<< endl << "or enter 0 to end the input: ";
cin >> number;
}
if (count > 0)
{
cout << endl << "The product is " << product << "." << endl;
}
By moving it around, I was able to end up here, but I keep ending up with errors. When I run the program, it prompts me to enter a while number, like expected. If I enter a valid number, it loops and asks me the same question. Then when I enter 0, it kicks out as usual, but it displays that the product is 0 no matter the numbers entered before.
Here is my attempt at adjusting it into a do while loop:
int main()
{
int number, product = 1, count = 0;
do
{
cout << "Enter a whole number to be included in the product" << endl << "or enter 0 to end the input: ";
cin >> number;
product = product * number;
count++;
}
while (number != 0);
{
if (count > 0)
cout << endl << "The product is " << product << "." << endl;
}
}

Answer 1

In the do .. while loop when you insert 0, first you multiply product by 0, than it exists. Therefore the product is always 0.
Move the product before:
int count = -1, number = 1, product = 1;
do
{
count++;
product = product * number; // you can use product *= number;
cout << "Enter a whole number to be included in the product" << endl << "or enter 0 to end the input: ";
cin >> number;
}
while (number != 0);
if (count > 0)
cout << endl << "The product is " << product << "." << endl;
Note: my code does not use additional if and still preserve the same functionality.

Answer 2

test number!=0 before assigning product = product*nuumber
otherwise, when user enters 0, you multiply by 0 and exit the loop

Answer 3

The problem is that in the do-while version, when the user inputs 0 this line:
product = product * number;
is executed, whereas in the while version not.
Because of this the product will always be 0.
If the number is 0 just don't multiply product.

Answer 4

Your problem was the number input on exit is 0, which makes your whole product equal to 0. Try this logic:
#include <iostream>
int main() {
int number = 0, product = 1, count = 0;
do {
std::cout << "Enter a whole number to be included in the product" << std::endl << "or enter 0 to end the input: ";
std::cin >> number;
if (number > 0) {
product = product * number;
count++;
}
} while (number != 0);
{
if (count > 0)
std::cout << std::endl << "The product is " << product << "." << std::endl;
}
}

Answer 5

If you just want to solve the problem that you are getting a 0 as your answer, then the problem is due to the following lines
cin >> number;
product = product * number;
you take the number which is 0 and multiply it with the product and obviously the result will be 0.
you can fix it by putting a break statement.
cin >> number;
if(number == 0)
break;
product = product * number;
However, in general I am not sure what you are achieving by trying to solve this problem i.e. converting a while to a do-while.

Answer 6

int number, product = 1, count = 0;
cout << "Enter a whole number to be included in the product"
<< endl << "or enter 0 to end the input: ";
cin >> number; // you enter a non-0 number here
while (number != 0) // you now loop until you hit 0 ...
{
product = product * number;
count++;
cout << "Enter a whole number to be included in the product"
<< endl << "or enter 0 to end the input: ";
cin >> number; // you overwrite the non-0 number you had previously input
}
if (count > 0)
{
cout << endl << "The product is " << product << "." << endl;
}
Without knowing the full context of your program, I'm guessing here, but you can probably rewrite it as:
int number = 0, product = 1, count = 0;
do
{
cout << "Enter a whole number to be included in the product"
<< endl << "or enter 0 to end the input: ";
cin >> number;
if (number != 0)
{
count++;
product *= number;
}
} while (number != 0); // exit the loop when you have a non-zero entry
if (count > 0)
{
cout << endl << "The product is " << product << "." << endl;
}
Or ...
int number = 0, product = 1;
do
{
cout << "Enter a whole number to be included in the product"
<< endl << "or enter 0 to end the input: ";
cin >> number;
if (number != 0)
{
product *= number;
}
} while (number != 0); // exit the loop when you have a non-zero entry
cout << endl << "The product is " << product << "." << endl;
You can avoid the 2nd condition since you are excluding 0 from potential inputs, and simply always output a product.

Answer 7

You are increasing count regardless of the input you get. First check if the input was zero (your abort input).
Change
count++
to
if (number)
count++;