Values of Argv when something is not entered from command line

Hi I was wondering what values would argv[1] or argv[2] be, if i failed to provide it with command line argume开发者_如何学Cnts

You've gotten an amazing number of incorrect answers to this. With nothing entered on the command line, argv[0] will still normally contain the name of the program, so argc will be 1. argv[argc] will contain a null pointer (always, on every conforming implementation of C or C++). In the C standard that requirement is at the second bullet of §5.1.2.1.1/2. In the C++ standard it's at §3.6.1/2.

It would be garbage NULL.

Therefore you should always first test the argc (argument count) before trying to access the command line arguments.

See this for more detailed information.

a segfault if you are lucky, garbage if you aren't.

The only safe way to use argv, is to treat it as an array of argc elements.

for (int ii = 0; ii < argc; ++ii)
{
    // safe to use argv[ii];
    cout << argv[ii];
}

int ix = somevalue;
if (ix >= 0 && ix < argc)
{
    // safe to use argv[ix];
}

Note to Jerry. A segfault is what you get when you de-reference NULL on most architectures.