How do you call error in C++?

I'm working on Bjarne Stroustrup's Chapter 3 in Programming: Principles and Pr开发者_如何学编程actice Using C++

Prompt the user to enter the age or the recipient and assign it to an int variable age. Have your program write "I hear you just had a birthday and You are age years old." If age is 0 or less or 110 or more, call error("you're kidding!").

cout<<"Enter the age of "<<friend_name<< ".\n";
int age=0;
cin>>age;
if (age==0)
    cout<<"you're kidding!";

if (age>=110)
    cout<<"you're kidding!";

if (age!=0, 110)
    cout<<"I hear you just had a birthday and you are " <<age<< " years old.\n";

I tried to do the code above but It kept giving me

"you're kidding! I hear you you just had a birthday and you are 0 years old"

but I don't think that is right. I think it's supposed to do one or the other and not both but I don't know how to make it do that.

if (age!=0, 110) is your problem. The comma operator returns the right-most expression, so that code is equivalent to if(110).

if (age!=0, 110)

Thats not proper syntax for a conditional. You need to do:

if ( age != 0 && age < 110 )

One problem is this: if (age!=0, 110). That's not doing what you think it is. If you want to test of the age is greater than zero and less than 110 the test would be:

if ((age > 0) && (age < 110)) 

Also, the problem specification says you are to output "you're kidding" for negative ages, too. You're not handling that.

#include <iostream>
using namespace std;
int main()
{
    int age;
    cout <<"Enter age of the recipient:\n";
    cin >> age;
    if (age != 0  && age < 110)
    {
        cout <<"I hear you just had a birthday and you are "<<age<<" years old.\n";
    }
   else
    {
        cout <<"Youre kidding.\n";
    }

} 

Does this code help?

#include <iostream>
#include <cmath>
#include <string>
#include <algorithm>
#include <vector>
using namespace std;
int main(){ 
cout<< "Write the age of the recipient\n";
int age;
cin>>age;
if(age<=0 || age>=110){
    cout<<"you're kidding!"<<endl;}
else{
cout<< " I hear you just had a birthday and you are "<<age<< " years old.";
}

return 0; }