reject unsupported options and disable default input file name

code/ysolve.f90

@@ -35,22 +35,42 @@
         CHARACTER(100) :: num1char
 
         !First, make sure the right number of inputs have been provided
-        IF(COMMAND_ARGUMENT_COUNT().EQ.0)THEN
-          ! read from itape
-          read_itape = .true.
-        ELSE IF(COMMAND_ARGUMENT_COUNT().EQ.1)THEN
+        IF(COMMAND_ARGUMENT_COUNT().EQ.1)THEN
           CALL GET_COMMAND_ARGUMENT(1,num1char)   !first, read in the two values
         ELSE
           WRITE(*,*)'ERROR, TOO MANY COMMAND-LINE ARGUMENTS(MORE THAN ONE). STOPPING'
           STOP
         ENDIF
 
-        read_stdin = (num1char=="-")
 
-        IF(read_itape)THEN
-          itape_name = "itape"
-          WRITE(*,*) "Read from itape"
-        ELSE IF(read_stdin)THEN
+        IF(num1char(1:1) == "-") THEN
+
+          if(num1char=="-h") then
+            write(*,'(a)') "usage: ex [-h] -|input_file"
+            write(*,'(a)') ""
+            write(*,'(a)') "positional arguments:"
+            write(*,'(a)') " -                 read from std_in"
+            write(*,'(a)') " input_file        input file name"
+            write(*,'(a)') ""
+            write(*,'(a)') "optional arguments:"
+            write(*,'(a)') " -h                show this help message and exit"
+
+            stop
+          else if (num1char=="-") then
+            read_stdin = .true.
+          else
+            WRITE(*,*)'ERROR, UNSUPPORTED OPTION ', trim(num1char), '. STOPPING'
+            STOP
+          end if
+
+        ELSE
+
+        END IF
+
+
+
+
+        IF(read_stdin)THEN
           WRITE(*,*) "Read from STDIN"
         ELSE 
           itape_name = num1char