Unexpected results on exception while doing file I/O - c++

Question

I have a small code with some file I/O
bool loadConfigFile(std::string configFileName)
{
std::ifstream configFile;
try
{
configFile.open(configFileName, std::ifstream::in);
if(true != configFile.good())
{
throw std::exception("Problem with config file");
}
} catch (std::exception &e)
{
fprintf(stderr, "There was an error while opening the file: %s\n %s\n" , configFileName, e.what());
configFile.close();
}
configFile.close();
return true;
}
And everytime I launch the program without the file provided as a parameter I get some rubbish on output (random characters) or an unexpected error in runtime. What am I doing wrong here ?

Answer 1

"%s" expects an null terminated char array as its input but the code is passing configFileName, which is a std::string. Either use std::string::.c_str() or use std::cerr instead:
std::cerr << "There was an error while opening the file: "
<< configFileName << '\n'
<< e.what() << '\n';
Note that the ifstream constructor has a variant that accepts the filename to open and the destructor will close the stream if it is open so the explicit calls to open() and close() can be omitted:
try
{
std::ifstream configFile(configFileName);
if (!configFile.is_open())
{
throw std::exception("Failed to open '" + configFileName + "'");
}
}
catch (const std::exception& e)
{
// Handle exception.
std::cerr << e.what() << '\n';
return false;
}