Question

I have the following code:

int main(int argc, char *argv[])
{
  if(strcmp(argv[1],"-e")==0)
  { 
    //perform code
  }

  //code if argv[1] is not "-e"

return 0;
}

When I take out the whole if statement:

if(strcmp(argv[1], "-e")==0)

my code if strcmp(argv[1], “-e”) == 0) is not “-e” works fine. But when I leave it in, my code only works for when the if statement above produces true. Any ideas on why this may happen? For example:

If I compile with argv[1] not commented out:

//example program will be an executable

exampleProgram -e < a.txt works but exampleProgram < a.txt doesn’t work. Any ideas why?

Answer 1

Simple, if you don’t send any argument to the program then args[1] doesn’t exist and you are trying to access to an unassigned memory position.

You may do something like this:

int main(int argc, char *argv[])
{
  if(argc > 1 && strcmp(argv[1],"-e")==0)
  { 
    //perform code
  }

  //code if argv[1] is not "-e"

return 0;
}