How can i stop a user from inputting a number as a decimal in an integer variable

1

hi there

i am very now to programming and have just got my first assignment.
I give the user three lines of options with the choice of 1,2 or 3. i am now stress testing the program and if for instance 2.5 is entered into the “choice” variable the program goes haywire! any help would be much appreciated! here is the program

#include<iostream>
#include<iomanip>

using namespace std;

int main()

{

int choice;
double totalrepay;
double eachrepay;
double interest;
double purchase;
char response;

do
{
cout&lt;&lt;"		Hire Purchase calculation Programme

“;
cout<<” ***************************************************
";
cout<<"1. Immediate Payment (10% reduction)
";
cout<<"2. Medium Term Payment (10% Increase, 12 Payments)
";
cout<<"3. Long term Payment (30% Increase, 36 Payments)
“;
cout<<” Please enter your number of your choice
";
cin>>choice;

            if (choice&lt;1 || choice&gt;3)
            do
            {
            cout&lt;&lt;"Your choice is invalid, please re-enter your choice

";
cin>>choice;
}
while (choice<1 || choice>3);

            cout&lt;&lt;"Please enter the Cost of your purchase.

";
cin>>purchase;

            if(choice==1)
            {
            totalrepay=0;
            eachrepay=0;
            interest=0;
            
            cout&lt;&lt;fixed&lt;&lt;setprecision(2)&lt;&lt;"The total cost of your repayments is €"&lt;&lt;totalrepay;
            cout&lt;&lt;endl;
            cout&lt;&lt;fixed&lt;&lt;setprecision(2)&lt;&lt;"The cost of each repayment is €"&lt;&lt;eachrepay;
            cout&lt;&lt;endl;
            cout&lt;&lt;fixed&lt;&lt;setprecision(2)&lt;&lt;"The cost of your interest is €"&lt;&lt;interest;
            cout&lt;&lt;endl;
            }
            
            else if(choice==2)
            {
            totalrepay=purchase*1.1;
            eachrepay=totalrepay/12;
            interest=purchase*0.1;
            
            cout&lt;&lt;fixed&lt;&lt;setprecision(2)&lt;&lt;"The total cost of your repayments is €"&lt;&lt;totalrepay;
            cout&lt;&lt;endl;
            cout&lt;&lt;fixed&lt;&lt;setprecision(2)&lt;&lt;"The cost of each repayment is €"&lt;&lt;eachrepay;
            cout&lt;&lt;endl;
            cout&lt;&lt;fixed&lt;&lt;setprecision(2)&lt;&lt;"The cost of your interest is €"&lt;&lt;interest;
            cout&lt;&lt;endl;
            }
            
            else if(choice==3)
            {
            totalrepay=purchase*1.3;
            eachrepay=totalrepay/36;
            interest=purchase*0.3;
            
            cout&lt;&lt;fixed&lt;&lt;setprecision(2)&lt;&lt;"The total cost of your repayments is €"&lt;&lt;totalrepay;
            cout&lt;&lt;endl;
            cout&lt;&lt;fixed&lt;&lt;setprecision(2)&lt;&lt;"The cost of each repayment is €"&lt;&lt;eachrepay;
            cout&lt;&lt;endl;
            cout&lt;&lt;fixed&lt;&lt;setprecision(2)&lt;&lt;"The cost of your interest is €"&lt;&lt;interest;
            cout&lt;&lt;endl;
            }
            
            else
            cout&lt;&lt;"I don't know how you got here

"<<endl;

cout&lt;&lt;"Do you want another go? y/n

";
cin>>response;
cout<<endl;
}
while (response==‘y’ || response==‘Y’);

system ("pause");
return 0;

}