basic_string::_S_construct null not valid

Question

I am reading an input file from the command line.

int main(int argc, char **argv)
{
    Scene myScene;
string filename = argv[1];
myScene = Parser(filename);
 ...
}

from another file I use the parser function which is declerated like that;

Scene Parser(string filename)
{
 string line;
 ifstream myfile (filename.c_str());
 ...
 return scene;
}

I am getting the error; terminate called after throwing an instance of 'std::logic_error' what(): basic_string::_S_construct null not valid

Program received signal SIGABRT, Aborted.

I have searched the error. I think it is because of these lines. But I cannot find the actual reason. Can anybody help me?

You must never say argv[1] if you don't check argc > 1 beforehand. — Kerrek SB
– Kerrek SB, Commented Jan 11, 2014 at 22:41

Halim Qarroum · Accepted Answer · 2014-01-11 22:41:51Z

11

This means that filename is NULL in Parser, probably because you are not passing any arguments to your program's command line.

Make sure to always check whether the expected number of arguments are passed to your program. For instance, you could do :

int main(int argc, char *argv[]) {
   if (argc != NUMBER_OF_EXPECTED_ARGUMENTS) {
      exit(EXIT_FAILURE);
   }
   // ...
   string filename(argv[1]);
   Scene myScene = Parser(filename);
   // ...
}

answered Jan 11, 2014 at 22:41

Halim Qarroum

14.1k4 gold badges48 silver badges75 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Vlad from Moscow · Accepted Answer · 2014-01-11 22:43:40Z

5

It is possible that you forgot to specify command line arguments and as the result argv[1] is equal to NULL. You should check whether the user entered command line arguments. For example

int main(int argc, char **argv)
{
    Scene myScene;
    string filename;
    if ( 1 < argc ) filename.assign( argv[1] );

answered Jan 11, 2014 at 22:43

Vlad from Moscow

313k27 gold badges204 silver badges358 bronze badges

Collectives™ on Stack Overflow

basic_string::_S_construct null not valid

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related