validating if value enter is an integer - c++

Question

First of all I am new to C++, can you guys help me with validating if value enter is an integer? And if my while statement in int(main) can be replace with a function.
#include <iostream>
using namespace std;
int validateNumb (int numb, int lim){
//takes a num, limit and checks if number is within limit
while (numb>=lim) { //if outside limit
cout << "Invalit input, try again with number (less than " << lim <<"): ";
cin >> numb; //assign user input value
}
cout << "Your integer is: " << numb << "\n\n"; //display input value
return numb;
}
int main() {
//variables
int num1, num2, num3, sum;
int limnum1, limnum2, limnum3;
//Welcome message
cout << "Hello & Welcome to E&M Ls1\n\n\n";
//First Number
cout << "Please Define the limit for First integer: ";
while (!(cin >> limnum1)) //if input is not true
{
cout << "Error!! Invalit input, please enter the First integer: ";
cin.clear();
cin.ignore(50, '\n');
}
cout << "Please Enter the First Integar that is (less than " << limnum1 << "): ";
while (!(cin >> num1)) //if input is not true
{
cout << "Error!! Invalit input, please enter the First integer: ";
cin.clear();
cin.ignore(50, '\n');
}
num1 = validateNumb(num1, limnum1); //check condition
//Second Number
cout << "Please Define the limit for Second integer: ";
while (!(cin >> limnum2)) //if input is not true
{
cout << "Error!! Invalit input, please enter the Second integer: ";
cin.clear();
cin.ignore(50, '\n');
}
cout << "Please Enter the Second Integar that is (less than " << limnum2 << "): ";
while (!(cin >> num2)) //if input is not true
{
cout << "Error!! Invalit input, please enter the Second integer: ";
cin.clear();
cin.ignore(50, '\n');
}
num2 = validateNumb(num2, limnum2); //check condition
//Third Number
cout << "Please Define the limit for Third integer: ";
while (!(cin >> limnum3)) //if input is not true
{
cout << "Error!! Invalit input, please enter the Third integer: ";
cin.clear();
cin.ignore(50, '\n');
}
cout << "Please Enter the Third Integar that is (less than " << limnum3 << "): ";
while (!(cin >> num3)) //if input is not true
{
cout << "Error!! Invalit input, please enter the Third integer: ";
cin.clear();
cin.ignore(50, '\n');
}
num3 = validateNumb(num3, limnum3); //check condition
//Sum for num1+num2+num3
sum = num1+num2+num3;
cout << "Sum of " << num1 <<" & " << num2 <<" & " << num3 <<" is: " << sum << ""; //display input value
cout<<"_______________________"<<endl;
cout<<"Thank you & Goodbye"<<endl; //end of the program
return 0;
}

Answer 1

bool is_integer(float k)
{
return std::floor(k) == k;
}
This solution should work for all possible values of k. I am pretty sure this is a case where you can safely compare floats using ==.
and yes your main can be broken into functions, maybe something like...
int getFirstNumber(){
int num =0;
// copy your code to get the first number
return num;
}
int getSecondNumber(){
int num =0;
// copy your code to get the second number
return num;
}
int getThirdNumber(){
int num =0;
// copy your code to get the thirdnumber
return num;
}
int sum(int a,int b,int c){
return (a+b+c);
}
int main(){
int a,b,c,d =0;
a = getFirstNumber;
b = getSecondNumber;
c = getThirdNumber;
d = sum(a,b,c);
return 0;
}
EDIT: I see you want to check if the number is in a valid range...
here:
// Returns true if x is in range [low..high], else false
bool inRange(unsigned low, unsigned high, unsigned x)
{
return ((x-low) <= (high-low));
}