CODEWITHSUNDEEP
c++iostreamcin
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Reputation: 2134

std::cin error state and variable changing

I thought that, if cin enters an error state, the variable it is streaming into remains unchanged. However, the following seems to be a counterexample:

#include <iostream>
using namespace std;

int main()
{
  cout << "Enter int: ";

  int i = 5;
  cin >> i;

  if(cin.fail()) cout << "failed \n";
  cout << "You entered: " << i << "\n";
}

Running:

Enter int: g
failed 
You entered: 0

Where did I go oh so wrong?

Upvotes: 0

Views: 199

Answers (1)

n. m. could be an AI
n. m. could be an AI

Reputation: 119847

The behaviour has changed in C++11. Failed integer extraction now sets the variable to 0.

GCC 4.8 exhibits the new behaviour even without -std=c++11 flag, which is probably a bug/limitation of the library. There's only one libstdc++, and it doesn't know which compiler flags were used to compile main.

Upvotes: 1

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