The First Bug

The value of argc was correct, so lets move on a step and see what happens.

     (gdb) next
     20	    printf( "Usage: ecount <word>\n");
     (gdb) list
     15
     16	  /* check we have a parameter */
     17
     18	  if( argc = 1 )
     19	  {
     20	    printf( "Usage: ecount <word>\n");
     21	    exit(1);
     22	  }
     23
     24	  /* Make our own local copy of argv[1] */
     (gdb) print argc
     $2 = 1
     (gdb)
     

Here we see that execution moved into the if() statement, which we didn't expect based on the value of argc. I have listed the code to remind myself of the surrounding structure, then checked the value of argc again.

argc is now 1, not 2! Looking closer at the code we see that the comparison operator in the if() statement was incorrectly written as = instead of ==. This assigned 1 to argc and returned 1 as the expression value, so the if evaluated as true and execution went into the if block.