Program name
It is useful to programmatically access a program's name, e.g. for determining whether the user ran "python hello.py", or "python hellocaller.py", a program importing the code from "hello.py".
C
C has difficulty accessing source code filenames, because C code must be compiled into an executable. However, C can access the executable's filename.
<lang c>#include <stdio.h>
int main(int argc, char **argv) { printf("Executable: %s\n", argv[0]);
return 0; }</lang>
C++
C++ has difficulty accessing source code filenames, because C code must be compiled into an executable. However, C++ can access the executable's filename.
<lang cpp>#include <iostream>
using namespace std;
int main(int argc, char **argv) { cout << "Executable: " << argv[0] << endl;
return 0; }</lang>