added code to print out positions of incorrect tokens

lexicalStructure.lex

@@ -81,6 +81,8 @@ SCHAR \\n|\\t|\\\"|[^\"\n\\]
 {ID}			{if(DEBUG) {printf( "ID:			%s	(%d)\n", yytext, ID);} 				else {return ID;}}
 
 \n				{line_number++; column_number = 1;}
-.				{column_number++;}
+\t				{column_number++;}
+" "				{column_number++;}
+.				{column_number++; return 1999;}
 
 %%

runner.c

@@ -79,6 +79,9 @@ int run(FILE *alpha) {
             }
             continue;
 	}
+   	if(token == 1999){
+                printf("On line number %d and column number %d we have an invalid character:%s\n",line_number,column_number,yytext);
+                }
 	column_number += yyleng;
     }