C++ Loop back beginning if the result is false - c++

Question

I am very new to C++ and still studying. The below scenario just came to my mind and I was trying to figure it out how to do this.
Scenario is as below:-
User inputs a number
then I store it in x
next is to check whether the input number is an int or float
if int, then pop up a message "Entered Number is not a Decimal Number" and go back to the beginning and inform the user to re-enter a number
if the entered number is float then I round it to the nearest int and pop up a message cout<<"Nearst Rounded Number is : "<<round(x)<<endl;
I assume this can be done with a loop, but I cannot figure it out.
#include <iostream>
#include <cmath>
using namespace std;
int main()
{
float x,y;
cout<<"Enter Number Here : ";
cin>>x;
{
if ( (x- int(x) == 0))
cout<<"Entered Number is not a Decimal Number"<<endl<<endl;
else
cout<<endl;
cout<<"Nearst Rounded Number is : "<<round(x)<<endl;
}
}

Answer 1

while(true) {
//(your existing code goes here)
cout << "Do you want to run the program again either types yes or no" << endl;
cin >> answer;
if (answer != 'yes' && answer != 'Yes')
break;
}
It should work. Else you can keep one bool variable in if else part and validate them below and break the while loop until your condition satisfy.

Answer 2

I believe this is what you wanted:
int main() {
string input_str;
float input_float = 0;
while (true) {
cout << "Enter number here: ";
cin >> input_str;
input_float = stof(input_str); //stof converts string to float
if (input_float != 0) {
if (input_float == int(input_float)) cout << "Entered number is not a decimal, please try again." << endl;
else break;
}
//TODO: Catch any exceptions thrown by stof (Ex: User inputs a letter)
}
cout << "Nearest Rounded number is: " << round(input_float)<<endl;
return 0;
}
Bye!
Edit: Changed the code a bit and removed a bug.

Answer 3

I have changed your code a bit to take input continuously. while(cin>>x) means the program is taking input constiniously until EOF. Then when you find a decimal number, it breaks.
#include <iostream>
#include <cmath>
using namespace std;
int main()
{
float x,y;
cout<<"Enter Number Here : ";
while(cin>>x)
{
if ( (x- int(x) == 0))
cout<<"Entered Number is not a Decimal Number"<<endl<<"Enter Number Here : ";
else
{
cout<<"Nearst Rounded Number is : "<<round(x)<<endl;
break;
}
}
}
By the way I will advise you to spend a bit more time to find out the solution on your own before posting here.

Answer 4

first of all Why is “using namespace std;” considered bad practice?
second - use a loop with a boolean flag to indicate when you want the exit the loop
#include <iostream>
#include <cmath>
int main()
{
float x,y;
bool flag = true;
while(flag)
{
std::cout<<"Enter Number Here : ";
std::cin>>x;
{
if ( (x- int(x) == 0))
std::cout<<"Entered Number is not a Decimal Number"<<std::endl;
else{
std::cout<<std::endl;
std::cout<<"Nearst Rounded Number is : "<<round(x)<<std::endl;
flag = false;
}
}
}
}

Answer 5

Your code needs improvements like indentations and the use of loop conditions otherwise your program will not rerun again.
#include <iostream>
#include <cmath>
using namespace std;
int main()
{
float x,y;
bool correctinputFlag=false;
do()
{
cout<<"Enter Number Here : ";
cin>>x;
if ( (x- int(x) == 0))
{
cout<<"Entered Number is not a Decimal Number"<<endl<<endl;
}
else
{
cout<<endl;
cout<<"Nearst Rounded Number is : "<<round(x)<<endl;
correctinputFlag=true;
}
}while(correctinputFlag==false);
}