If an invalid operation is attempted on a stream, the stream variable will subsequently evaluate to false. This can be used to allow the programmer to detect and handle errors as follows...

IOissues.cpp

 #include <fstream>
 #include <string>
 using namespace std; 
   
 int main() { 

     string fileName = "myfile.txt"; 
     ifstream inputData; 
       
     //open the file, if error, bail out 
     inputData.open(fileName); 
     if (! inputData) { 
         cout << "File " << fileName << " could not be opened.\n"; 
         cout << "program terminated.\n"; 
         return -1; 
     } 
       
     ...