how can i check my data type?

[GraxGunz]

#include <iostream>
using namespace std;
 
int main()
{
   int num;
   int mul;
 
   cout << "Enter a number: ";
   cout >> num;
 
   //if()
 
   mul= num*10;
   cout << "This is 10 times the numbers << mul << endl;
 
   /*   
   else
   {
      cout << "Input error, Please try again."
      return main();
    }*/
 
   return 0;
 
 

this is the simple program i wrote, an d i want to know is there anyway to check my data type of num so that the program will only run when user enter an integer value. it will prompt "Input error, Please try again." when user enter a float, string or char values, can someone help me, i have no ideal how to do that....

[weaknessforcats]

You are using C++ so cin >> to an int and then call cin.fail(). If cin.fail() returns true and int was not entered. Before you retry, you will need to empty the stdin buffer to remove the non-int data.

[GraxGunz]

[Before you retry, you will need to empty the stdin buffer to remove the non-int data.]

i got your ideal, but how can i remove the non int data at stdin? does c++ have any reserve word? sorry, i just start leaned few months ago... still not understand very well...

[GraxGunz]

i had try cin.clear(); but it seems didn't works...
note: i'm using dev c++

[weaknessforcats]

cin.clear() only resets the good/fail flag. The bad data is still there.

You can't really cear the stdin buffer since you don't know what is there.

Your could write a function that takes an int by reference and returns true if an int was entered.

The function does a cin >> an int.
If this works you have your int and the function returns true.
Otherwise, the function calls cin.clear() to reset the fail bit. and returns false. You don't have your int and the bad data is still in stdin.

bool GetInt(int& thedata)
{
    cin >> thedata;
    if (cin.fail() == true)
    {
        //no int
        cin.clear();  //reset fail flag
        return false;
    }
    return true;  //got the int
}
 

The function doesn't try to recover the stdin since it's job was to fetch an int. The function that calls this one can decide what to do. In tis case, a single byte is fetched and discarded and the function is tried again:

int main()
{
    int myInt;
    while (GetInt(myInt) == false)
    {
        char trash;
        cin >> trash;
    }
    cout << myInt << endl;
}
 

This should give you the idea.

[GraxGunz]

i got that! thank you very much ^.^