How Do You Troubleshoot a C Program That Prints a Warning Message like “expects argument of type ‘int’, but argument 2 has type ‘char *’ [-Wformat=]”?

Problem scenario
You compile a C program (with gcc foobar.cc) but you get an error message like this:

basicprog.c:5:13: warning: format '%d' expects argument of type 'int', but argument 2 has type 'char *' [-Wformat=]
printf ("y is a %d\n",y);

What do you do to not get this error?

Solution
While the code compiles, the executable may not run.  A compilation error can be benign.  For this case, string characters need a special syntax to be printed out.  

Here is a line that will produce this error (with a variable named "y"):

   printf ("y is a %d\n", y);

Here is a similar but corrected line that will be error free:

  printf ("y is a %s\n",y);

The "%d" is appropriate for printing integer variables.  For string variables, use "%s" syntax.

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