C++: how do I check if the cin buffer is empty?

Question

How do you check to see if the user didn\'t input anything at a cin command and simply pressed enter?

Answer 1

int main(){ 
string str[100];
std::cout<<"Hello how are you ? \n";
std::cin>>str;
if(str.length() > 0){
// If input is seen
}
else{
// If input is not seen
}
}

Any problem let me know.