Programming Forums > Application Development > C++

IceCold19 · Jan 18th, 2007, 9:09 PM

I need to read in a value, declared as

int anIntVariable = 0;

via cin

cin >> anIntVariable

I now need to check if it is indeed an int value. How do I check if this is something other than an integer?

grumpy · Jan 18th, 2007, 9:28 PM

Check the state of the stream. If it can't complete an operation, it will be in an error state. For example;

(Toggle Plain Text)

#include <iostream>

int main()
{
    int value;
    while (std::cin.eof())
    {
       std::cin >> value;
       if (std::cin.bad())    // if bad data in stream
          std::cin.clear();   //  clear the error state
    }
}

Will loop forever attempting to read an int from cin until an end-of-file indication occurs. I'll leave it as an exercise as to how a user can generate an end-of-file condition in cin, as the means of doing that are system dependent.

Jan 18th, 2007, 9:09 PM	#1
IceCold19 Newbie Join Date: Jan 2007 Posts: 2 Rep Power: 0	Find if something is an int I need to read in a value, declared as int anIntVariable = 0; via cin cin >> anIntVariable I now need to check if it is indeed an int value. How do I check if this is something other than an integer?

Jan 18th, 2007, 9:28 PM	#2
grumpy Programming Guru Join Date: Jun 2005 Location: Adelaide, South Australia Posts: 1,254 Rep Power: 5	Check the state of the stream. If it can't complete an operation, it will be in an error state. For example; (Toggle Plain Text) #include <iostream> int main() { int value; while (std::cin.eof()) { std::cin >> value; if (std::cin.bad()) // if bad data in stream std::cin.clear(); // clear the error state } } #include <iostream> int main() { int value; while (std::cin.eof()) { std::cin >> value; if (std::cin.bad()) // if bad data in stream std::cin.clear(); // clear the error state } } Will loop forever attempting to read an int from cin until an end-of-file indication occurs. I'll leave it as an exercise as to how a user can generate an end-of-file condition in cin, as the means of doing that are system dependent.

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Programming Forums > Application Development > C++

Find if something is an int