I open two files, one input and one output. I'd like to handle exceptions for both of them, so by looking at some examples, I made this:
std::ifstream readFile;
readFile.exceptions (std::ifstream::failbit | std::ifstream::badbit);
//set the flags for stream bits that indicate failure if ON
std::ofstream writeFile;
writeFile.exceptions (std::ifstream::failbit | std::ifstream::badbit);
try{
readFile.open(inputFileName);
writeFile.open(outputFileName);
function(readFile, writeFile);
readFile.close();
writeFile.close();
}
catch(std::ifstream::failure &readErr) {
std::cerr << "\n\nException occured when reading a file\n"
<< readErr.what()
<< std::endl;
return -1;
}
catch(std::ofstream::failure &writeErr) {
std::cerr << "\n\nException occured when writing to a file\n"
<< writeErr.what()
<< std::endl;
return -1;
}
This seems like a reasonable solution, but I get a warning:
warning: exception of type 'std::ios_base::failure' will be caught [enabled by default]
catch(std::ofstream::failure &writeErr) {
^
The code does it's thing, but I'm still interested in improving my code. Where have I wronged?
No you can't. The typedef of std::ifstream::failure
and std::ofstream::failure
are both defined to be std::ios_base::failure
.
The best thing you could do is wrap the individual calls with try-catch:
try
{
readFile.open(inputFileName);
}
catch(std::ifstream::failure &readErr)
{
}
try
{
writeFile.open(outputFileName);
}
catch(std::ofstream::failure &writeErr)
{
}
Or check the state of the streams individually in the catch block to see who failed.